@article{spears_lloyd_flores_krafka_hyda_grimes_2024, title={Chromium propionate in turkeys: effect on performance and animal safety}, volume={103}, ISSN={["1525-3171"]}, DOI={10.1016/j.psj.2023.103195}, abstractNote={Two hundred and eighty-eight male Nicholas Large White turkey poults were used to determine the effect of supplementing turkeys with chromium propionate (Cr Prop) from 1 to 84 d of age on performance and animal safety. Treatments consisted of Cr prop supplemented to provide 0, 0.2, or 1.0 mg Cr/kg diet. One mg of supplemental Cr is 5 times (x) the minimal concentration of Cr Prop that enhanced insulin sensitivity in turkeys. Each treatment consisted of 8 floor pens with 12 poults per pen. Turkeys were individually weighed initially, and at the end of the starter 1 (d 21), starter 2 (d 42), grower 1 (d 63), and grower 2 phase (d 84). On d 85, blood was collected from the wing vein in heparinized tubes from 2 turkeys per pen for plasma chemistry measurements. A separate blood sample was collected from the same turkeys in tubes containing K2EDTA for hematology measurements. Turkey performance was not affected by treatment during the starter 1 phase. Gain was greater (P = 0.024) and feed/gain lower (P = 0.030) for turkeys supplemented with Cr compared with controls during the starter 2 phase. Over the entire 84-d study turkeys supplemented with Cr had greater (P = 0.005) ADG and tended (P = 0.074) to gain more efficiently than controls. Gain (P = 0.180) and feed/gain (P = 0.511) of turkeys supplemented with 0.2 mg Cr/kg did not differ from those receiving 1.0 mg Cr/kg over the entire 84-d study. Feed intake was not affected by treatment. Body weights of turkeys supplemented with Cr were heavier (P = 0.005) than controls by d 84. Chromium supplementation did not affect hematological measurements and had minimal effect on plasma chemistry variables. Results of this study indicates that Cr Prop supplementation can improve turkey performance, and is safe when supplemented to turkey diets at 5x the minimal concentration that enhanced insulin sensitivity.}, number={1}, journal={POULTRY SCIENCE}, author={Spears, J. W. and Lloyd, K. E. and Flores, K. and Krafka, K. and Hyda, J. and Grimes, J. L.}, year={2024}, month={Jan} }
 @article{spears_lloyd_krafka_hyda_grimes_2024, title={Chromium propionate in turkeys: effects on insulin sensitivity}, volume={103}, ISSN={["1525-3171"]}, DOI={10.1016/j.psj.2023.103215}, abstractNote={The objective of this study was to evaluate the effects of dietary chromium (Cr), as Cr propionate (Cr Prop), on measures of insulin sensitivity in turkeys. Plasma glucose and non-esterified fatty acid (NEFA), and liver glycogen concentrations were used as indicators of insulin sensitivity. One-day-old Nicholas Large White female poults (n = 336) were randomly assigned to dietary treatments consisting of 0 (control), 0.2, 0.4, or 0.6 mg supplemental Cr/kg diet. Each treatment consisted of 12 replicate cages with 7 turkeys per cage. Final BW were taken on d 34, and on d 35 two birds from each cage were sampled for plasma glucose and NEFA, and liver glycogen determination at the initiation (fed state) and termination (fasted state) of a 24-h fast. Following a 24-h fast, two turkeys per cage were refed (refed state) their treatment diet for 4 h, and then harvested. Feed/gain and ADG did not differ between control and Cr-supplemented turkeys over the 34-d study, but feed intake tended (P = 0.071) to be greater for controls than turkeys receiving 0.4 mg Cr/kg diet. Fed turkeys had greater plasma glucose (P = 0.002) and liver glycogen (P = 0.001) concentrations, and lower (P = 0.001) NEFA concentrations than fasted birds. Turkeys refed after fasting had greater (P = 0.001) plasma glucose and liver glycogen concentrations, and lower (P = 0.001) plasma NEFA levels than fed turkeys. Liver glycogen and plasma NEFA concentrations did not differ among control and Cr-supplemented birds in the fed, fasted, or refed state. Plasma glucose concentrations were not affected by treatment in fed or fasted turkeys. Turkeys supplemented with 0.2 or 0.4 mg Cr/kg and refed after fasting had lower (quadratic, P = 0.038) plasma glucose concentrations than controls. Plasma glucose concentrations in refed birds did not differ among Cr-supplemented turkeys. The lower plasma glucose concentration in Cr-supplemented turkeys following refeeding is consistent with Cr enhancing insulin sensitivity.}, number={1}, journal={POULTRY SCIENCE}, author={Spears, J. W. and Lloyd, K. E. and Krafka, K. and Hyda, J. and Grimes, J. L.}, year={2024}, month={Jan} }
 @article{spears_lloyd_krafka_hyda_grimesy_2024, title={Research Note: Chromium propionate for turkeys: effect on tissue chromium concentrations and human food safety}, volume={103}, ISSN={["1525-3171"]}, DOI={10.1016/j.psj.2023.103196}, abstractNote={This study was conducted to determine the effect of supplementing turkey diets with chromium propionate (Cr Prop) on Cr concentrations in tissues consumed by humans. Nicholas White male d-old poults were used in this study. Treatments consisted of 0, 0.20, or 1.0 mg supplemental Cr/kg diet. Each treatment consisted of 8 replicate floor pens with 12 poults housed per pen. Diets were fed ad libitum for 84 d. At the end of the study, 2 turkeys per pen were euthanized and samples of liver, breast muscle, kidney, and skin with adhering fat were collected from a similar location in each bird for Cr analysis. Orthogonal contrasts were used to compare the 2 Cr supplemented treatments to the control (0 added Cr) and 0.20 mg Cr to 1.0 mg Cr/kg diet. When expressed on a DM or wet tissue basis, liver (P = 0.001) and muscle (P = 0.015) Cr concentrations were greater in turkeys supplemented with Cr compared with controls. Chromium concentrations in liver were also greater (P = 0.001) in turkeys supplemented with 1.0 mg Cr/kg than those receiving 0.20 mg Cr/kg. Concentrations of Cr in kidney and skin + fat were not affected by treatment. Considering the adequate intake of Cr established for humans, supplementation of Cr Prop at up to 1.0 mg Cr/kg diet would have minimal effect on total Cr intake by humans.}, number={1}, journal={POULTRY SCIENCE}, author={Spears, J. W. and Lloyd, K. E. and Krafka, K. and Hyda, J. and Grimesy, J. L.}, year={2024}, month={Jan} }
 @article{yan-mei_de_kai-wen_spears_hai-tao_yen-ling_fa-long_2023, title={Dietary copper supplementation modulates performance and lipid metabolism in meat goat kids}, volume={22}, ISSN={["2095-3119"]}, DOI={10.1016/j.jia.2022.08.066}, abstractNote={Forty-eight male Lezhi black goat kids with similar body weight ((12.09±1.70) kg) and age ((60±5) d) were used to determine the effect of dietary copper (Cu), in the form of reagent grade Cu sulfate (CuSO4·5H2O), on performance, serum lipid profile, and the relative mRNA abundance of genes involved in lipid metabolism. Goat kids were stratified by body weight and randomly assigned to one of 4 treatment groups. Each treatment consisted of 12 replicate pens with each pen containing one goat kid. Treatment groups received the basal diet with no supplemental Cu (control), basal diet plus 10 mg of Cu kg−1 of dry matter (DM), basal diet plus 20 mg of Cu kg−1 of DM, or basal diet plus 30 mg of Cu kg−1 of DM. Goats were housed individually in pens and fed a high-concentrate pelleted diet for 60 d. Average daily gain, average daily feed intake and feed:gain of goats were not affected by dietary Cu supplementation (P>0.10). No differences were detected in serum total cholesterol, triglyceride, and high density lipoprotein cholesterol concentrations of goat kids fed with different Cu concentrations (P>0.05). However, serum low density lipoprotein cholesterol concentrations decreased linearly (P=0.01) as the concentration of dietary Cu increased. Intramuscular fat content of longissimus muscle increased (P=0.002) quadratically and liver Cu concentrations increased (P<0.001) linearly as dietary Cu concentration increased. Compared with the control, dietary supplementation of 20 mg Cu kg−1 DM decreased the relative mRNA abundance of fatty acid-binding protein 4 (P=0.01) and lipoprotein lipase (P=0.05), and tended to decrease the relative mRNA abundance of carnitine palmitoyltransferase I (P=0.06) in longissimus muscle of goats. The relative mRNA abundance of peroxisome proliferator-activated receptor alpha (P<0.001), carnitine acetyltransferase (P=0.001), and carnitine palmitoyltransferase I (P=0.001) were also decreased in liver by Cu supplementation. These results indicate that dietary supplementation of Cu modified lipid metabolism by increasing muscular fat and decreasing serum low density lipoprotein cholesterol, and the modification might be associated with the reduction of relative mRNA abundance of genes for oxidation of long-chain fatty acid in muscle and liver of Lezhi black goat kids.}, number={1}, journal={JOURNAL OF INTEGRATIVE AGRICULTURE}, author={Yan-mei, Zhang and De, Ao and Kai-wen, Lei and Spears, Jerry W. and Hai-tao, Shi and Yen-ling, Huang and Fa-long, Yang}, year={2023}, month={Jan}, pages={214–221} }
 @article{spears_2023, title={Evaluation of Trace Mineral Sources}, volume={39}, ISSN={["1558-4240"]}, DOI={10.1016/j.cvfa.2023.05.002}, abstractNote={Several trace mineral sources, including inorganic, numerous organic, and hydroxychloride sources, are available for dietary supplementation or inclusion in a free-choice supplement. Inorganic forms of copper and manganese differ in their bioavailability. Although research results have been variable, organic and hydroxychloride trace minerals are generally considered more bioavailable than inorganic sources. Research indicates that fiber digestibility is lower in ruminants fed sulfate trace minerals compared with hydroxychloride and some organic sources. Compared with free-choice supplements, individual dosing with rumen boluses or injectable forms ensures that each animal receives the same quantity of a trace mineral.}, number={3}, journal={VETERINARY CLINICS OF NORTH AMERICA-FOOD ANIMAL PRACTICE}, author={Spears, Jerry W.}, year={2023}, month={Nov}, pages={413–424} }
 @article{loh_mezzomo_gomes_tangredi_guimaraes_gifford_miller_levenson_thorndyke_spears_et al._2023, title={The Influence of Trace Mineral Source on Rumen Trace Mineral Solubility and In-Vitro Fiber Digestion in Steers Fed a Lactating Dairy Diet}, volume={101}, ISSN={["1525-3163"]}, DOI={10.1093/jas/skad281.473}, abstractNote={Abstract}, journal={JOURNAL OF ANIMAL SCIENCE}, author={Loh, Huey Yi and Mezzomo, Rafael and Gomes, Daiany I and Tangredi, Briana V and Guimaraes, Octavio and Gifford, Ryan J. and Miller, Alexandra C. and Levenson, Jonah R. and Thorndyke, Meghan P. and Spears, Jerry W. and et al.}, year={2023}, month={Nov}, pages={398–399} }
 @misc{spears_brandao_heldt_2022, title={INVITED REVIEW: Assessing trace mineral status in ruminants, and factors that affect measurements of trace mineral status}, volume={38}, ISSN={["2590-2865"]}, DOI={10.15232/aas.2021-02232}, abstractNote={The purpose of this article is to review criteria for assessing copper, zinc, manganese, and selenium status in ruminants. Factors that affect measurements of trace mineral status also will be discussed. Published scientific literature was the primary source of information reviewed. When assessing mineral status, it is always good to analyze the diet or forages being consumed for the mineral of interest as well as other minerals that may affect its requirement. Liver is the best indicator of both low and excess Cu status. Plasma Cu concentrations do not decrease below normal values until liver Cu stores are mostly depleted, but a plasma Cu concentration less than 0.4 mg/L suggests Cu deficiency. Severe Zn deficiency can be diagnosed based on extremely low plasma or serum Zn concentrations (less than 0.5 mg/L) or on clinical signs of Zn deficiency that respond to Zn supplementation. It is important to note that infections or acute stress may cause plasma Zn concentrations to temporarily decrease to levels consistent with Zn deficiency. There is currently no reliable indicator of marginal Zn deficiency. Several criteria have been measured in an attempt to assess Mn status. However, no criteria have been demonstrated to accurately predict Mn deprivation. Whole blood or liver Se concentrations are useful in assessing Se status. When interpreting whole blood or liver Se concentrations, it is important to consider whether dietary Se is being derived from organic or inorganic sources. The most appropriate measurement criteria to assess trace mineral status in ruminants depend on the trace mineral being considered. Liver copper is generally a good measure of low as well as excess Cu status. Liver or whole blood Se concentrations are reliable measures of Se status if one takes into account the source of dietary Se. Unless clinical deficiency signs are apparent, it is more difficult to assess Zn and Mn status. In the absence of disease or stress, plasma or serum Zn concentrations below 0.5 mg/L suggest possible severe deficiency. No reliable predictor of marginal Zn deficiency has been determined. Currently, no reliable indicator of Mn status has been identified.}, number={3}, journal={APPLIED ANIMAL SCIENCE}, author={Spears, J. W. and Brandao, V. L. N. and Heldt, J.}, year={2022}, month={Jun}, pages={252–267} }
 @article{guimaraes_wagner_spears_brandao_engle_2022, title={Trace mineral source influences digestion, ruminal fermentation, and ruminal copper, zinc, and manganese distribution in steers fed a diet suitable for lactating dairy cows}, volume={16}, ISSN={["1751-732X"]}, DOI={10.1016/j.animal.2022.100500}, abstractNote={High solubility of certain trace minerals (TM) in the rumen can alter nutrient digestibility and fermentation. The objectives of the present studies were to determine the effects of TM source on 1) nutrient digestibility and ruminal fermentation, 2) concentrations of soluble Cu, Zn, and Mn in the rumen following a pulse dose of TM, and 3) Cu, Zn, and Mn binding strength on ruminal digesta using dialysis against a chelating agent in steers fed a diet formulated to meet the requirements of a high producing dairy cow. Twelve Angus steers fitted with ruminal cannulae were adapted to a diet balanced with nutrient concentrations similar to a diet for a high producing lactating dairy cow for 21 d. Steers were then randomly assigned to dietary treatments consisting of 10 mg Cu, 40 mg Mn, and 60 mg Zn/kg DM from either sulfate (STM), hydroxychloride (HTM) or complexed trace minerals (CTM). The experimental design did not include a negative control (no supplemental Cu, Mn, or Zn) because the basal diet did not meet the National Research Council requirement for Cu and Zn. Copper, Mn, and Zn are also generally supplemented to lactating dairy cow diets at concentrations approximating those supplied in the present study. Following a 14-d adaptation period, total fecal output was collected for 5-d. Following the fecal collection period, rumen fluid was collected for Volatile fatty acid (VFA) parameters. On the following day, the same diet was provided for 14 d, without supplemental Cu, Zn, and Mn. This period served as a wash-out period. A pulse dose of 100, 400, and 600 mg of Cu, Zn, Mn, respectively, from either STM, HTM, or CTM, was administered via ruminal cannulae to the steers on day 15. Over a 24-h period ruminal samples were obtained every 2-h. Following centrifugation, the supernatant was analyzed for Cu, Mn, and Zn. Ruminal solid digesta samples from times 0, 12, and 24 h after bolus dosing were exposed to dialysis against Tris-EDTA. Digestibility of NDF and ADF were lesser in STM vs. HTM and vs. CTM supplemented steers. Steers receiving HTM and CTM had greater total VFA concentrations than STM, and molar proportions of individual VFA were not affected by treatment. Ruminal soluble Cu and Zn concentrations were greater post dosing in STM and CTM supplemented steers at 2, 4, and 6 h for Cu and 4, 6, 8, 10 and 12 h for Zn when compared to HTM supplemented steers. The release of Cu and Zn from ruminal solid digesta following dialysis against Tris-EDTA at 12 and 24 h postdosing was greater for steers receiving HTM compared to those receiving STM or CTM. Results indicate trace mineral source impacts: 1) how tightly bound Cu and Zn are to ruminal solid digesta; 2) fiber digestion; 3) and ruminal total VFA concentrations.}, number={4}, journal={ANIMAL}, author={Guimaraes, O. and Wagner, J. J. and Spears, J. W. and Brandao, V. L. N. and Engle, T. E.}, year={2022}, month={Apr} }
 @article{fellner_durosoy_kromm_spears_2021, title={Effects of supplemental zinc on ruminal fermentation in continuous cultures}, volume={37}, ISSN={2590-2865}, url={http://dx.doi.org/10.15232/aas.2020-02104}, DOI={10.15232/aas.2020-02104}, abstractNote={ABSTRACT Objective Our objective was to determine the effect of dietary Zn supplementation on microbial fermentation. Materials and Methods Five dual-flow continuous culture fermentors were offered 15 g of DM/d of a corn silage–based diet that supplied 64 mg of Zn/kg of diet DM. The source of supplemental Zn (30 and 120 mg/kg) was either analytical grade zinc oxide (ZnO) or a greater-purity potentiated zinc oxide (HiZox; Animine, Annecy, France). A total of 5 diets were fermented: (1) control (no supplemental Zn); (2) 30 mg/kg supplemental Zn from ZnO; (3) 120 mg/kg supplemental Zn from ZnO; (4) 30 mg/kg supplemental Zn from HiZox, and (5) 120 mg/kg supplemental Zn from HiZox. Diets were replicated (n = 3), and each replication lasted 8 d with 4 d for adjustment to diets followed by 4 d of data collection. Results and Discussion Rumen soluble Zn (as-is basis) increased with supplemental Zn, and the increase tended to be greater with HiZox compared with ZnO. Total VFA concentrations were not affected by treatment. Molar percentage of acetate increased and propionate decreased with HiZox compared with ZnO; the effects were primarily due to the 120 mg/kg concentration. Zinc oxide decreased branched-chain fatty acids, isobutyrate and isovalerate, when compared with HiZox. Supplemental Zn increased culture pH before and after feeding compared with control; the increase was greatest with 30 mg/kg HiZox. Methane was similar between control and HiZox but significantly reduced with ZnO. Zinc supplementation reduced ammonia-N concentration when compared with control; the decrease was due primarily to ZnO, which resulted in much lower ammonia-N compared with HiZox. Implications and Applications Both supplemental Zn sources increased rumen-soluble Zn (as-is basis), but their effect on fermentation was not similar. The divalent Zn2+ is known to combine with Cl− to form various Zn-Cl complexes (ZnCl+, ZnCl2, ZnCl3−), which may exert differing toxicities and explain the disparate effect on microbial fermentation.}, number={1}, journal={Applied Animal Science}, publisher={American Registry of Professional Animal Scientists}, author={Fellner, V. and Durosoy, S. and Kromm, V. and Spears, J.W.}, year={2021}, month={Feb}, pages={27–32} }
 @article{guimaraes_jalali_wagner_spears_engle_2021, title={Trace mineral source impacts rumen trace mineral metabolism and fiber digestion in steers fed a medium-quality grass hay diet}, volume={99}, ISSN={["1525-3163"]}, DOI={10.1093/jas/skab220}, abstractNote={Abstract}, number={9}, journal={JOURNAL OF ANIMAL SCIENCE}, author={Guimaraes, Octavio and Jalali, Sam and Wagner, John J. and Spears, Jerry W. and Engle, Terry Eugene}, year={2021}, month={Sep} }
 @article{spears_siciliano_pratt-phillips_lloyd_goertzen_krafka_hyda_rounds_2020, title={Chromium propionate improves insulin sensitivity in horses following oral concentrate consumption}, volume={98}, ISSN={["1525-3163"]}, DOI={10.1093/jas/skaa278.160}, abstractNote={Abstract}, journal={JOURNAL OF ANIMAL SCIENCE}, author={Spears, Jerry W. and Siciliano, Paul and Pratt-Phillips, Shannon and Lloyd, Karen and Goertzen, Ellen and Krafka, Kristi and Hyda, Jill and Rounds, Whitney}, year={2020}, month={Nov}, pages={88–88} }
 @article{spears_lloyd_siciliano_pratt-phillips_goertzen_mcleod_moore_krafka_hyda_rounds_2020, title={Chromium propionate increases insulin sensitivity in horses following oral and intravenous carbohydrate administration}, volume={98}, ISSN={["1525-3163"]}, DOI={10.1093/jas/skaa095}, abstractNote={Abstract}, number={4}, journal={JOURNAL OF ANIMAL SCIENCE}, author={Spears, Jerry W. and Lloyd, Karen E. and Siciliano, Paul and Pratt-Phillips, Shannon and Goertzen, Ellen W. and McLeod, Sarah J. and Moore, Jennifer and Krafka, Kristi and Hyda, Jill and Rounds, Whitney}, year={2020}, month={Apr} }
 @article{jalali_lippolis_ahola_wagner_spears_couch_engle_2020, title={Influence of supplemental copper, manganese, and zinc source on reproduction, mineral status, and performance in a grazing beef cow-calf herd over a 2-year period}, volume={36}, ISSN={["2590-2865"]}, DOI={10.15232/aas.2020-01982}, abstractNote={ABSTRACT Objective This experiment evaluated the effects of Cu, Mn, and Zn source on mineral status, reproduction, and performance of grazing beef cattle in eastern Colorado. Materials and Methods Crossbred (Angus and Angus × Hereford; n = 261) 3-yr-old beef cows were stratified by expected calving date, BW, BCS, and liver Cu status and randomly assigned to 1 of 6 replicates. Replicates were then assigned to 1 of 2 treatments (n = 40–45 cows per replicate), resulting in 3 replicates per treatment for the 2-yr experiment. Treatments consisted of (1) inorganic–organic trace mineral combination (IOC; 75% of Cu, Mn, and Zn from sulfate forms and the remaining 25% from organic AA complexes) and (2) hydroxy trace minerals (HTM; 100% from hydroxychloride forms). Replicates were rotated among pastures approximately every 28 d to minimize pasture effects. Free-choice mineral feeders were used to provide NASEM (2000) recommended concentrations of Cu, Mn, and Zn continuously for 2 yr. Blood samples and liver biopsies were obtained from every cow before the initiation of the experiment and then from a subgroup of animals (20 random animals per replicate) at the end of yr 1 (d 335 of the experiment) and 2 (d 638 of the experiment). Results and Discussion Over the 2-yr experiment, mineral intake, cow BW, BCS, pregnancy rate to AI, and overall pregnancy rate did not differ across treatments. Calf weaning weights were also not affected by trace mineral source. At the end of yr 1 and yr 2, liver Cu concentrations were greater (P ≤ 0.05) in HTM- compared with IOC-supplemented cows. Liver Zn concentrations were greater (P 0.05) by trace mineral source. Implications and Applications Overall productivity of grazing beef cows and their calves over a 2-yr period were similar in cattle supplemented with hydroxy or a combination of sulfate and organic trace minerals. Liver Cu and Zn concentrations were greater in cows fed HTM.}, number={5}, journal={APPLIED ANIMAL SCIENCE}, author={Jalali, S. and Lippolis, K. D. and Ahola, J. K. and Wagner, J. J. and Spears, J. W. and Couch, D. and Engle, T. E.}, year={2020}, month={Oct}, pages={745–753} }
 @article{guimaraes_wagner_spears_engle_2020, title={Influence of trace mineral source on digestion, ruminal volatile fatty acid and soluble mineral on steers fed a dairy type diet balanced to meet requirements for a high producing lactating dairy cow}, volume={98}, ISSN={["1525-3163"]}, DOI={10.1093/jas/skaa054.231}, abstractNote={Abstract}, journal={JOURNAL OF ANIMAL SCIENCE}, author={Guimaraes, Octavio and Wagner, John and Spears, Jerry and Engle, Terry}, year={2020}, month={Nov}, pages={133–133} }
 @article{huang_luo_xiao_lin_spears_2020, title={Research Note: Responses of growth performance, immune traits, and small intestinal morphology to dietary supplementation of chromium propionate in heat-stressed broilers}, volume={99}, ISSN={0032-5791}, url={http://dx.doi.org/10.1016/j.psj.2020.07.005}, DOI={10.1016/j.psj.2020.07.005}, abstractNote={This study was conducted to investigate the dose responses of growth performance, immune traits, and small intestinal morphology to dietary supplementation of chromium propionate (CrPro) in heat-stressed broilers. A total of 252 1-day-old Cobb 500 male broilers were randomly assigned to 6 treatments with 7 replicate cages of 6 birds per cage. The dietary treatments consisted of a basal diet supplemented with 0, 0.2, 0.4, 0.8, 1.6, and 3.2 mg/kg Cr in the form of CrPro. The birds had ad libitum access to feed and tap water for an experimental period of 42 D. For induction of heat stress, the house temperature was set at 35°C ± 2°C from 22 to 42 D of age. No differences were detected among treatments in growth performance during the experimental period (P > 0.05). Serum IgA concentrations were not affected by treatment (P > 0.05). However, a quadratic response was detected for serum IgG (P < 0.01) and IgM (P < 0.01) concentration as dietary Cr supplementation was increased. The highest response of IgG and IgM in serum was observed for broilers fed a diet supplemented with 0.2 mg of Cr/kg. Dietary supplementation of Cr had no impacts on villus height, crypt depth, or the ratio of villus height to crypt depth in the jejunum and ileum. A quadratic response of villus height and the ratio of villus height to crypt depth and a linear response of crypt depth to increased dietary Cr supplementation were observed in the duodenum (P < 0.01). The results indicate that CrPro supplementation could modify the intestinal morphology of the duodenum and influence serum IgG and IgM concentrations in heat-stressed broiler chickens. Based on the results of this experiment, the 0.2-mg Cr/kg diet from CrPro increases immune response and intestinal health in heat-stressed broilers.}, number={10}, journal={Poultry Science}, publisher={Elsevier BV}, author={Huang, Y.L. and Luo, Q.H. and Xiao, F. and Lin, X. and Spears, J.W.}, year={2020}, month={Oct}, pages={5070–5073} }
 @article{spears_2020, title={Ruminal microbiota mineral requirements to optimize performance on different diets}, volume={98}, ISSN={["1525-3163"]}, DOI={10.1093/jas/skaa054.243}, abstractNote={Abstract}, journal={JOURNAL OF ANIMAL SCIENCE}, author={Spears, Jerry W.}, year={2020}, month={Nov}, pages={139–139} }
 @article{guimaraes_loh_thorndykel_tillquistl_spears_engle_2020, title={The influence of trace mineral source on copper, manganese, and zinc binding strength to rumen digesta in cattle fed a high forage-based diet}, volume={98}, ISSN={["1525-3163"]}, DOI={10.1093/jas/skaa278.772}, abstractNote={Abstract}, journal={JOURNAL OF ANIMAL SCIENCE}, author={Guimaraes, Octavio and Loh, Huey Yi and Thorndykel, Meghan P. and Tillquistl, Nicole M. and Spears, Jerry W. and Engle, Terry E.}, year={2020}, month={Nov}, pages={443–443} }
 @article{guimaraes_loh_thorndyke_tillquist_spears_engle_2020, title={The influence of trace minerals source on copper, manganese, and zinc binding strength to rumen digesta in cattle fed a corn silage-based diet}, volume={98}, ISSN={["1525-3163"]}, DOI={10.1093/jas/skaa278.771}, abstractNote={Abstract}, journal={JOURNAL OF ANIMAL SCIENCE}, author={Guimaraes, Octavio and Loh, Huey Yi and Thorndyke, Meghan P. and Tillquist, Nicole M. and Spears, Jerry W. and Engle, Terry E.}, year={2020}, month={Nov}, pages={442–442} }
 @article{spears_2019, title={Boron, Chromium, Manganese, and Nickel in Agricultural Animal Production}, volume={188}, DOI={10.1007/s12011-018-1529-1}, abstractNote={This paper provides an overview of research that has been conducted with manganese (Mn), chromium (Cr), nickel (Ni), and boron (B) in poultry, swine, and ruminants. Manganese is an essential trace mineral that functions as an enzyme component and enzyme activator. A deficiency of Mn results in a variety of bone abnormalities, and Mn deficiency signs have been observed under practical conditions in poultry and cattle. Chromium can potentiate the action of insulin, but whether Cr is an essential trace mineral is controversial. Insulin sensitivity has been enhanced by Cr in cattle, swine, and broilers. Responses to Cr supplementation have been variable. Production responses to Cr supplementation have been most consistent in animals exposed to various stressors (heat, cold, weaning, etc). The legality of supplementing Cr to animal diets varies among countries, Cr sources, and animal species. A specific biochemical function for Ni and B has not been identified in mammals. Signs of Ni deficiency have been produced experimentally in a number of animal species. Nickel may affect rumen microbial fermentation in ruminants, as Ni is a component of bacterial urease and cofactor F 430  in methanogenic bacteria. There is little evidence that dietary Ni limits animal production under practical conditions. Beneficial effects of B supplementation on growth and bone strength have been seen in poultry and swine, but results have been variable.}, number={1}, journal={BIOLOGICAL TRACE ELEMENT RESEARCH}, author={Spears, Jerry W.}, year={2019}, pages={35–44} }
 @article{spears_lloyd_pickworth_huang_krafka_hyda_grimes_2019, title={Chromium propionate in broilers: human food and broiler safety}, volume={98}, ISSN={0032-5791}, url={http://dx.doi.org/10.3382/ps/pez444}, DOI={10.3382/ps/pez444}, abstractNote={Chromium propionate (Cr Prop) is approved by the U.S. Food and Drug Administration Center for Veterinary Medicine for supplementation to broiler diets up to 0.20 mg Cr/kg diet. A 49-D study was conducted to: 1) determine the safety of Cr Prop when supplemented at 2 and 10 times (×) the approved feeding level over the normal life span of broilers, and 2) determine the effects of supplementing Cr Prop on Cr concentrations of tissues consumed by humans. On day zero, 216 Ross 708 broilers were stratified by weight within sex and randomly assigned to treatments. Dietary treatments were 0 (control), 0.40, and 2.0 mg supplemental Cr/kg diet from Cr Prop. There were 6 replicate cages each of male and female broilers per treatment. At the end of the study blood was collected for determination of plasma biochemical measurements and tissue samples were collected for Cr analysis. Supplementing 0.40 mg Cr/kg diet (2×) did not adversely affect broiler performance, mortality, plasma biochemical measurements or Cr concentrations in breast muscle, skin with adhering fat, or liver. Chromium propionate supplemented at 2.0 mg Cr/kg (10×) did not affect Cr concentrations in breast muscle or skin with adhering fat, but increased (P < 0.05) liver Cr concentrations. Supplementing Cr Prop at 10× the approved feeding level decreased feed intake and gain in male but not female broilers from days 21 to 49. Results of this study support the safety of Cr Prop in broiler diets, and indicate that Cr Prop supplementation to broiler diets at 2 or 10× the approved feeding level does not present a human health concern.}, number={12}, journal={Poultry Science}, publisher={Elsevier BV}, author={Spears, J.W. and Lloyd, K.E. and Pickworth, C.A. and Huang, Y.L. and Krafka, K. and Hyda, J. and Grimes, J.L.}, year={2019}, month={Dec}, pages={6579–6585} }
 @article{budde_sellins_lloyd_wagner_heldt_spears_engle_2019, title={Effect of zinc source and concentration and chromium supplementation on performance and carcass characteristics in feedlot steers}, volume={97}, ISSN={["1525-3163"]}, DOI={10.1093/jas/skz016}, abstractNote={Four hundred crossbred steers were used in a randomized complete block design to investigate the effects of supplemental Zn source and concentration, and dietary Cr on performance and carcass characteristics of feedlot steers fed a steam-flaked corn-based finishing diet. Steers were blocked by initial BW within cattle source (3 sources) and randomly assigned within block to 1 of 5 treatments. Before the initiation of the experiment, trace mineral supplement sources were analyzed for Zn and Cr. Zinc and Cr concentrations of the Zn sources were used to balance all dietary treatments to obtain correct Zn and Cr experimental doses. Treatments were the addition of: 1) 90 mg Zn/kg DM from ZnSO4 and 0.25 mg Cr/kg DM from Cr propionate (90ZS+Cr); 2) 30 mg Zn/kg DM from Zn hydroxychloride and 0.25 mg Cr/kg DM from Cr propionate (30ZH+Cr); 3) 90 mg Zn/kg DM from Zn hydroxychloride and 0.25 mg Cr/kg DM from Cr propionate (90ZH+Cr); 4) 60 mg Zn/kg DM from ZnSO4 and 30 mg Zn/kg DM from Zn methionine (90ZSM); and 5) 90 mg Zn/kg DM from Zn hydroxychloride (90ZH). Steers were individually weighed on d-2 and on 2 consecutive days at the end of the experiment. Initial liver biopsies were obtained from all steers at processing. Equal numbers of pen replicates per treatment were slaughtered at a commercial abattoir on day 162, 176, and 211; individual carcass data and final liver samples were collected. Total finishing dietary Zn and Cr concentrations were 118.4, 58.2, 114.2, 123.0, and 108.2 mg Zn/kg DM and 0.740, 0.668, 0.763, 0.767, and 0.461 mg Cr/kg DM, for treatments 1 to 5, respectively. Data were analyzed statistically using preplanned single degree of freedom contrasts. Steers receiving 90ZH+Cr had greater final BW (P < 0.04) and ADG (P < 0.03) when compared with steers receiving 90ZH. Additionally, hot carcass weight was 8.5 kg greater (P < 0.03) for 90ZH+Cr compared with 90ZH supplemented steers. Steers receiving 90ZH+Cr had greater longissimus muscle area when compared with steers receiving 90ZSM. Dry matter intake, G:F, morbidity and mortality, and all other carcass measurements were similar across treatments. These data indicate that under the conditions of this experiment, Zn source and concentration had no impact on live performance, liver Zn and Cu concentrations, and carcass characteristics. Supplemental Cr in diets containing 90 mg of supplemental Zn/kg DM from ZH improved final BW, ADG, and hot carcass weights.}, number={3}, journal={JOURNAL OF ANIMAL SCIENCE}, author={Budde, Ashley M. and Sellins, Karen and Lloyd, Karen E. and Wagner, John J. and Heldt, Jeff S. and Spears, Jerry W. and Engle, Terry E.}, year={2019}, month={Mar}, pages={1286–1295} }
 @article{caldera_weigel_kucharczyk_sellins_archibeque_wagner_han_spears_engle_2019, title={Trace mineral source influences ruminal distribution of copper and zinc and their binding strength to ruminal digesta}, volume={97}, ISSN={["1525-3163"]}, DOI={10.1093/jas/skz072}, abstractNote={Eight crossbred steers (BW 719.0 ± 65.0 kg) with ruminal and duodenal cannulae were used to examine the effect of trace mineral (TM) source on digestibility; ruminal and duodenal solubility of Cu, Zn, and Mn; and in vitro release of Cu, Zn, and Mn from the solid fraction of ruminal digesta. Experiment 1 determined the effect of TM source on DM and NDF digestibility in steers fed a corn silage and steam-flaked corn-based diet. Treatments consisted of 10 mg Cu, 20 mg Mn, and 30 mg Zn/kg DM from either sulfate TM (STM) or hydroxy TM (HTM) sources. Following a 14-d adaptation period, total fecal output was collected for 5 d. Dry matter digestibility was not affected by treatment, but NDF digestibility tended (P < 0.09) to be greater in HTM vs. STM supplemented steers. In Exp. 2, steers were fed a diet without supplemental Cu, Zn, or Mn for 19 d. Steers were then administrated a pulse dose of STM or HTM (2× the National Research Council requirements for Cu, Mn, and Zn) via the rumen fistula. Ruminal and duodenal samples were obtained at 2-h intervals starting at -4 and ending at 24 h relative to dosing. Ruminal soluble Cu and Zn concentrations were affected by treatment, time, and treatment × time. Soluble concentrations and percent soluble Cu and Zn in ruminal digesta increased (P < 0.05) above 0-h values for 10 h following dosing with STM, but not HTM. Concentrations of Cu and Zn in ruminal solid digesta were also affected by treatment, time, and treatment × time. Steers dosed with STM had greater (P < 0.05) solid digesta Cu concentrations at 2 and 4 h but lesser (P < 0.05) concentrations from 6 to 20 h post-dosing than those receiving HTM. Ruminal solid digesta Zn concentrations were greater (P < 0.05) in HTM vs. STM-dosed steers from 6 through 24 h post-dosing. Distribution of Mn in ruminal digesta was affected by TM source, but to a lesser extent than Zn and Cu. Duodenal soluble TM concentrations were variable and not affected by treatment. Binding strength of TM to ruminal solid digesta was estimated at 0, 6, and 12 h post-dosing using dialysis against chelating agents. The percentage of Cu and Zn released from ruminal solid digesta by dialysis against Tris-EDTA was greater (P < 0.05) at 12 h post-dosing from steers receiving HTM vs. STM. Results indicate that Cu and Zn from HTM have low solubility in the rumen and appear to be less tightly bound to ruminal solid digesta than Cu and Zn from STM.}, number={4}, journal={JOURNAL OF ANIMAL SCIENCE}, author={Caldera, Emmanuel and Weigel, Brittney and Kucharczyk, Vicky N. and Sellins, Karen S. and Archibeque, Shawn L. and Wagner, John J. and Han, Hyungchul and Spears, Jerry W. and Engle, Terry E.}, year={2019}, month={Apr}, pages={1852–1864} }
 @article{shaeffer_lloyd_spears_2017, title={Bioavailability of zinc hydroxychloride relative to zinc sulfate in growing cattle fed a corn-cottonseed hull-based diet}, volume={232}, ISSN={["1873-2216"]}, DOI={10.1016/j.anifeedsci.2017.07.013}, abstractNote={A study was conducted to evaluate the bioavailability of zinc hydroxychloride (ZnOHCl) relative to Zn sulfate (ZnSO4) in growing steers. Sixteen Angus and Simmental steers (371 kg average initial weight) were fed a corn-cottonseed hull-based diet without supplemental Zn for 14 d. At the end of the 14-d depletion phase steers were randomly assigned within a breed to treatments consisting of supplemental Zn at 25 mg/kg DM from either ZnSO4 or ZnOHCl. Seven days after the initiation of Zn supplementation a 5-d total collection of feces and urine was conducted. Jugular blood samples were obtained on d 0 (prior to initiation of Zn treatments) and on d 40 of the study for plasma Zn determination. Dry matter intake, Zn intake and urinary Zn excretion were not affected (P > 0.10) during the metabolism phase. Apparent absorption and retention of Zn were greater (P < 0.01) in steers supplemented with ZnOHCl than in those supplemented with Zn SO4. Plasma Zn concentrations were similar across treatments on d 0 of the study. On d 40 of the study plasma Zn concentrations were higher (P < 0.05) in steers supplemented with Zn OHCl compared to those fed ZnSO4. Results of this study indicated that ZnOHCl is a more bioavailable source of Zn than ZnSO4 for growing cattle when supplemented to a diet with relatively low Zn bioavailability.}, journal={ANIMAL FEED SCIENCE AND TECHNOLOGY}, author={Shaeffer, G. L. and Lloyd, K. E. and Spears, J. W.}, year={2017}, month={Oct}, pages={1–5} }
 @article{spears_lloyd_krafka_2017, title={Chromium concentrations in ruminant feed ingredients}, volume={100}, ISSN={["1525-3198"]}, DOI={10.3168/jds.2016-12153}, abstractNote={Chromium (Cr), in the form of Cr propionate, has been permitted for supplementation to cattle diets in the United States at levels up to 0.50 mg of Cr/kg of DM since 2009. Little is known regarding Cr concentrations naturally present in practical feed ingredients. The present study was conducted to determine Cr concentrations in feed ingredients commonly fed to ruminants. Feed ingredients were collected from dairy farms, feed mills, grain bins, and university research farms. Mean Cr concentrations in whole cereal grains ranged from 0.025 mg/kg of DM for oats to 0.041 mg/kg of DM for wheat. Grinding whole samples of corn, soybeans, and wheat through a stainless steel Wiley mill screen greatly increased analyzed Cr concentrations. Harvested forages had greater Cr concentrations than concentrates, and alfalfa hay or haylage had greater Cr concentrations than grass hay or corn silage. Chromium in alfalfa hay or haylage (n = 13) averaged 0.522 mg/kg of DM, with a range of 0.199 to 0.889 mg/kg of DM. Corn silage (n = 21) averaged 0.220 mg of Cr/kg of DM with a range of 0.105 to 0.441 mg of Cr/kg of DM. By-product feeds ranged from 0.040 mg of Cr/kg of DM for cottonseed hulls to 1.222 mg of Cr/kg of DM for beet pulp. Of the feed ingredients analyzed, feed grade phosphate sources had the greatest Cr concentration (135.0 mg/kg). Most ruminant feedstuffs and feed ingredients had less than 0.50 mg of Cr/kg of DM. Much of the analyzed total Cr in feed ingredients appears to be due to Cr contamination from soil or metal contact during harvesting, processing, or both.}, number={5}, journal={JOURNAL OF DAIRY SCIENCE}, author={Spears, J. W. and Lloyd, K. E. and Krafka, K.}, year={2017}, month={May}, pages={3584–3590} }
 @article{brooks_grimes_lloyd_krafka_lamptey_spears_2016, title={Chromium propionate in broilers: effect on insulin sensitivity}, volume={95}, ISSN={["1525-3171"]}, DOI={10.3382/ps/pew018}, abstractNote={The objective of this study was to evaluate the effects of dietary chromium (Cr), as chromium propionate, on measures of insulin sensitivity. Liver and muscle glycogen, and plasma glucose and non-esterified fatty acid (NEFA) concentrations were used as indicators of insulin sensitivity. In total, 288 newly hatched male Ross broilers were divided into 4 dietary treatments consisting of 0 (control diet analyzed 0.43 to 0.45 mg Cr/kg), 0.2, 0.4, or 0.6 mg supplemental Cr/kg diet, resulting in 4 treatments with 9 replicate pens per treatment containing eight birds per pen. At d 21, 2 birds per cage were removed based on the greatest deviation from pen mean BW, resulting in each pen containing 6 birds for the final analyses. Final BW were taken on d 40, and on d 42 two birds from each pen were sampled for plasma NEFA, glucose, and muscle and liver glycogen determination at the initiation and termination of a 22 h fast. The remaining 2 fasted birds were sampled after a 30 min refeeding period. No differences were observed in feed intake, BW gain, or feed efficiency on d 21 or d 40. Liver glycogen tended (P=0.10) to be greater in Cr-supplemented chicks in the fed state, and muscle glycogen concentrations tended (P=0.07) to be greater in Cr-supplemented chicks compared with controls following fasting and refeeding. Plasma glucose concentrations were not affected by dietary Cr in the fed, fasted, or refed state. Plasma NEFA levels were not affected by treatment in fed or fasted birds. However, plasma NEFA concentrations were lower (P<0.01) in chicks supplemented with Cr than in controls following fasting and refeeding, suggesting that Cr increased insulin sensitivity. No differences were detected among birds supplemented with 0.2 or 0.4 mg Cr/kg, and among those receiving 0.4 or 0.6 mg Cr/kg. Results of this study indicate that Cr propionate supplementation of a control diet containing 0.43 to 0.45 mg Cr/kg enhanced insulin sensitivity.}, number={5}, journal={POULTRY SCIENCE}, author={Brooks, M. A. and Grimes, J. L. and Lloyd, K. E. and Krafka, K. and Lamptey, A. and Spears, J. W.}, year={2016}, month={May}, pages={1096–1104} }
 @article{li_hansen_borst_spears_moeser_2016, title={Dietary Iron Deficiency and Oversupplementation Increase Intestinal Permeability, Ion Transport, and Inflammation in Pigs}, volume={146}, ISSN={["1541-6100"]}, DOI={10.3945/jn.116.231621}, abstractNote={BACKGROUND
Understanding the influence of dietary iron deficiency and dietary iron oversupplementation on intestinal health is important for both animal production and human health.


OBJECTIVE
The aim of this study was to determine whether dietary iron concentration influences intestinal physiology, morphology, and inflammation in the porcine duodenum.


METHODS
Twenty-four male pigs (21 d old) were fed diets containing either 20 mg Fe/kg [low dietary iron (L-Fe)], 120 mg Fe/kg [adequate dietary iron (A-Fe); control], or 520 mg Fe/kg [high dietary iron (H-Fe)] by FeSO4 supplement (dry matter basis). After 32-36 d, the duodenum was harvested from pigs and mounted in Ussing chambers for the measurement of transepithelial electrical resistance (TER), short-circuit current, and (3)H-mannitol permeability. Intestinal morphology and inflammation were assessed by histologic examination, and proinflammatory gene expression was assessed by real-time polymerase chain reaction.


RESULTS
Compared with A-Fe-fed pigs, pigs fed L-Fe diets exhibited reduced TER (by 30%; P < 0.05). Compared with that of A-Fe-fed controls, the paracellular flux of (3)H-mannitol across the duodenal mucosa was higher (P < 0.05) in L-Fe-fed (>100%) and H-Fe-fed (∼4-fold) pigs; the L-Fe-fed and H-Fe-fed groups did not differ significantly from one another. Compared with the L-Fe-fed pigs, the A-Fe-fed and H-Fe-fed pigs had malondialdehyde concentrations 1.4- and 2.5-fold higher in the duodenum and 4.4- and 6.6-fold higher in the liver, respectively (P < 0.05). Neutrophil counts were higher in both the L-Fe-fed (by 3-fold) and H-Fe-fed (by 3.3-fold) groups than in the A-Fe-fed group; the L-Fe-fed and H-Fe-fed groups did not significantly differ from one another. Duodenal mucosal tumor necrosis factor α (TNFA), interleukin (IL) 1β, and IL6 relative gene expression was upregulated by 36%, 28%, and 45%, respectively, in H-Fe pigs (P < 0.05), but not in L-Fe pigs, compared with A-Fe pigs.


CONCLUSION
These data suggest that adequate but not oversupplementation of dietary iron in pigs is required to maintain intestinal barrier health and function.}, number={8}, journal={JOURNAL OF NUTRITION}, author={Li, Yihang and Hansen, Stephanie L. and Borst, Luke B. and Spears, Jerry W. and Moeser, Adam J.}, year={2016}, month={Aug}, pages={1499–1505} }
 @article{xiao_ao_zhou_spears_lin_huang_2016, title={Effects of Supplemental Chromium Propionate on Serum Lipids, Carcass Traits, and Meat Quality of Heat-Stressed Broilers}, volume={176}, ISSN={0163-4984 1559-0720}, url={http://dx.doi.org/10.1007/s12011-016-0852-7}, DOI={10.1007/s12011-016-0852-7}, abstractNote={This study was conducted to investigate the effects of chromium from chromium propionate (CrPro) on serum lipids, carcass traits, and breast meat quality in heat-stressed birds. A total of 210 1-day-old male broilers were randomly allotted by initial body weight (BW) into 5 treatments with 7 replicates with 6 birds per replicate pen for 42 days. The treatments included a basal corn-soybean meal diet and basal diet supplemented with 0.2, 0.4, 0.8, or 1.6 mg Cr/kg diet. Birds had ad libitum access to feed and distilled-deionized water at normal conditions for 1-3 weeks with little or no stress, and then birds were housed under heat stress conditions with 35 ± 2 °C ambient temperature for 4-6 weeks. Results showed that serum triglyceride (TG) (P = 0.0006) and low-density lipoprotein cholesterol (LDLC) (P = 0.0038) concentrations were decreased linearly as Cr dose increased. Compared with other groups, birds receiving 0.8 or 1.6 mg Cr/kg had lower TG (P = 0.0015). Compared to control birds, birds fed diets with 0.2, 0.4, 0.8, or 1.6 mg Cr/kg supplementation had lower LDLC (P = 0.0006). However, the total cholesterol (TC) and high density lipoprotein cholesterol (HDLC) concentrations in serum were not affected by treatment (P > 0.05). No difference was observed in BW, the relative weights of breast muscle, thigh muscle and abdominal fat (P > 0.05), and breast meat quality (Ph 15min , Ph 24h,  L * , a * , b * , cooking loss, shear force) among the treatments (P > 0.05). Results from this study indicated that CrPro supplementation could be beneficial to serum lipids metabolism of heat-stressed broiler chickens by decreasing TG and LDLC contents, but had no impacts on meat quality and carcass traits of the heat-stressed broilers.}, number={2}, journal={Biological Trace Element Research}, publisher={Springer Science and Business Media LLC}, author={Xiao, Fang and Ao, Degulina and Zhou, Bo and Spears, Jerry W and Lin, Xi and Huang, Yanling}, year={2016}, month={Sep}, pages={401–406} }
 @inproceedings{spears_2016, title={History of chromium and its relationship to glucose metabolism}, booktitle={2016 Cornell Nutrition Conference for Feed Manufacturers}, author={Spears, J. W.}, year={2016}, pages={1–8} }
 @article{huang_ashwell_fry_lloyd_flowers_spears_2015, title={Effect of dietary copper amount and source on copper metabolism and oxidative stress of weanling pigs in short-term feeding}, volume={93}, ISSN={["1525-3163"]}, DOI={10.2527/jas.2014-8082}, abstractNote={Forty-eight weanling barrows were used to determine the effects of amount and source of dietary Cu on Cu metabolism, oxidative stress in the duodenum, and VFA ratios in the cecum of weanling pigs in short-term feeding. At 21 d of age, newly weaned pigs were stratified by BW (7.03 ± 1.20 kg) and equally assigned to 1 of the following dietary treatments: 1) control (5 mg supplemental Cu/kg diet from CuSO4), 2) 225 mg supplemental Cu/kg diet from CuSO4, or 3) 225 mg supplemental Cu/kg diet from tribasic Cu chloride (TBCC). Pigs were housed 2 pigs per pen and were fed a complex diet until harvest on d 11 and 12. During harvest, bile and liver were obtained for mineral analysis, and liver samples were obtained for analysis of mRNA expression of Cu regulatory proteins. Digesta of duodenum, proximal jejunum, and ileum were collected for soluble Cu analysis. Mucosal scrapings of duodenum, proximal jejunum, and ileum were obtained for analysis of mucosal Cu concentration and mRNA expression of Cu regulatory proteins. Duodenal mucosal scrapings were also collected for analysis of malondialdehyde (MDA). Pigs fed high Cu had markedly greater (P < 0.0001) Cu concentrations in the duodenal, proximal jejunal, and ileal mucosa than controls. Copper in the duodenal mucosa was greater (P = 0.003) in CuSO4 than TBCC pigs. Duodenal MDA concentrations were greater (P = 0.003) in CuSO4 vs. control pigs and tended (P = 0.06) to be greater than in TBCC pigs. Duodenal antioxidant 1 (Atox1) mRNA was downregulated (P < 0.01) in pigs fed high Cu compared to controls and was not affected by Cu source. Compared with control pigs, those fed CuSO4 and TBCC had greater (P < 0.001) liver and bile Cu concentrations. Liver Cu was also greater (P = 0.0007) in TBCC than CuSO4-fed pigs. Hepatic Cu transporting β-polypeptide ATPase (Atp7b) was upregulated (P = 0.02) in the Cu-supplemented pigs compared with controls and did not differ among Cu sources. The acetate:propionate ratio in cecal contents was much greater in pigs supplemented with 225 mg Cu/kg diet than in controls. When fed at 225 mg Cu/kg diet, TBCC may cause less oxidative stress in the duodenum than CuSO4. Feeding weanling pigs increased Cu resulted in modulation of duodenal and liver at the transcription level.}, number={6}, journal={JOURNAL OF ANIMAL SCIENCE}, author={Huang, Y. L. and Ashwell, M. S. and Fry, R. S. and Lloyd, K. E. and Flowers, W. L. and Spears, J. W.}, year={2015}, month={Jun}, pages={2948–2955} }
 @article{brooks_grimes_lloyd_verissimo_spears_2013, title={Bioavailability in chicks of zinc from zinc propionate}, volume={22}, ISSN={["1537-0437"]}, DOI={10.3382/japr.2012-00525}, abstractNote={SUMMARY The purpose of this experiment was to evaluate the relative bioavailability of Zn from Zn propionate relative to feed-grade Zn sulfate using BW gain and bone Zn as response criteria. For the first 7 d posthatching, chicks were fed a semipurified starter diet deficient in Zn (22 mg of Zn/kg). From d 8 to 21 birds were fed a control (20 mg of Zn/kg) semipurified diet containing ground corn, soy protein concentrate, and dextrose. The control diet was supplemented with 0, 6, or 12 mg of Zn/kg of diet from feed-grade Zn sulfate or organic Zn propionate. Using corn in the diet increased the level of phytate, an important Zn antagonist in nonruminant animals. As supplemental dietary Zn increased, a dose-dependent increase was observed in feed intake, weight gain, total Zn intake, tibia Zn concentration, and total tibia Zn. Zinc supplementation improved FE (feed:gain), but not in a dose-dependent manner. Relative bioavailability of Zn was determined using weight gain, tibia Zn concentration, and total tibia Zn, assuming a value of 100% for feed-grade Zn sulfate. Using relative slope assay, relative bioavailability of Zn propionate was 119, 116, and 116% compared with Zn sulfate, respectively. We concluded, based on these results, that bioavailability of Zn from organic Zn propionate is greater than feed-grade Zn sulfate in the presence of dietary phytate.}, number={2}, journal={JOURNAL OF APPLIED POULTRY RESEARCH}, author={Brooks, M. A. and Grimes, J. L. and Lloyd, K. E. and Verissimo, S. and Spears, J. W.}, year={2013}, month={Jun}, pages={153–159} }
 @article{huang_wang_spears_lin_guo_2013, title={Effect of copper on performance, carcass characteristics, and muscle fatty acid composition of meat goat kids}, volume={91}, ISSN={0021-8812 1525-3163}, url={http://dx.doi.org/10.2527/jas.2012-5820}, DOI={10.2527/jas.2012-5820}, abstractNote={An experiment was conducted to determine the effects of dietary Cu on performance, carcass characteristics, and muscle fatty acid composition in meat goats. Thirty five Jianyang Big-ear goat (JYB) kids (average BW 20.3 ± 0.6 kg and age 3 to 4 mo) were stratified by weight and randomly assigned to 1 of 7 experimental treatments (n = 5 goats per treatment). Treatments consisted of: 1) control (no supplemental Cu; 14.3 mg Cu/kg DM), 2) 20 mg supplemental Cu/kg DM, 3) 40 mg supplemental Cu/kg DM, 4) 80 mg supplemental Cu/kg DM, 5) 160 mg supplemental Cu/kg DM, 6) 320 mg supplemental Cu/kg DM, and 7) 640 mg supplemental Cu/kg DM. Copper was supplemented from CuSO4•5H2O (25.2% Cu). Goats were individually fed a concentrate-hay based diet for 96 d. Performance was not affected by Cu concentration. Liver Cu concentration was increased (P < 0.01) with Cu supplementation. Goats supplemented with 0 or 20 mg Cu/kg DM had lower (P < 0.01) liver Cu concentrations than the other treatments. Backfat depth (P < 0.01) and intramuscular fat (IMF) content (P < 0.01) were also increased with Cu supplementation. However, Cu-supplemented goats had lower (P = 0.04) longissimus muscle area (LMA) compared with control. Dietary Cu supplementation increased the percentage of C14:0 (P < 0.01), C20:4 (P < 0.01), and total polyunsaturated fatty acids (P = 0.03), decreased C18:1 trans (P = 0.04), and tended to decrease C18:0 (P = 0.08) in LM. Other fatty acids detected were not affected by dietary Cu supplementation (P > 0.10). These results indicate that JYB goats can tolerate up to 640 mg Cu/kg DM for 96 d without adverse effects on performance, but fat deposition and fatty acid composition in the body could be altered by Cu supplementation as low as 20 mg/kg of diet with high concentrate-hay. Copper supplementation increased backfat depth, IMF, and percentage of polyunsaturated fatty acids in LM and decreased LMA in the carcass of JYB goats.}, number={10}, journal={Journal of Animal Science}, publisher={Oxford University Press (OUP)}, author={Huang, Y. L. and Wang, Y. and Spears, J. W. and Lin, X. and Guo, C. H.}, year={2013}, month={Oct}, pages={5004–5010} }
 @article{fry_spears_lloyd_o'nan_ashwell_2013, title={Effect of dietary copper and breed on gene products involved in copper acquisition, distribution, and use in Angus and Simmental cows and fetuses}, volume={91}, ISSN={["1525-3163"]}, DOI={10.2527/jas.2011-3888}, abstractNote={Copper (Cu) deficiency is a widespread problem in cattle across the United States and breed differences in Cu metabolism may contribute to this issue. Intracellular Cu is tightly regulated by transport and chaperone proteins, and to date, these mechanisms have not been elucidated to address breed differences in Cu metabolism, nor have these proteins been characterized in bovine fetal liver. Mature, pregnant Angus (n = 8) and Simmental (n = 8) cows (∼4 mo into gestation) were used in a 2 × 2 factorial arrangement of treatments. All cows were bred to Angus sires resulting in an Angus vs. Simmental × Angus comparison for fetuses. Cows were randomly assigned to corn silage-based diets that were either adequate (+Cu) or deficient (-Cu; 6.6 mg Cu/kg DM) in Cu. Diets were individually fed for 112 d. At the end of the study, cows were harvested to collect duodenal mucosa scrapes, liver samples, and fetal liver samples for mineral analysis and also for mRNA and protein analysis of Cu transport and chaperone proteins. Placentomes were also obtained for mineral analysis. Plasma Cu and liver Cu were affected by Cu, breed, and Cu × breed. Both of these Cu indices were less (P ≤ 0.05) in-Cu Simmentals (-CuS) than in-Cu Angus (- uA), but were similar among +Cu Simmental (+CuS) and +Cu Angus cows (+CuA). Duodenal Cu was less (P = 0.01) in-Cu vs. +Cu cows. Placentome Cu was less (P = 0.003) in-Cu vs. +Cu cows, and was also less (P = 0.03) in Simmentals vs. Angus. Fetal liver Cu was less (P = 0.002) in-Cu vs. +Cu fetuses, and was also less (P = 0.05) in Simmental × Angus vs. Angus. Abundance of Cu transporter1 (CTR1) protein and transcripts for Cu transporters and chaperones were not affected by Cu or breed in liver and were not affected by Cu in the intestine. Duodenal Ctr1 was less (P = 0.04) and CTR1 tended (P = 0.10) to be less in Simmentals vs. Angus. Expression of Atp7a tended (P = 0.08) to be less in Simmentals than in Angus. In fetal liver, expression of antioxidant 1 (Atox1), cytochrome c oxidase assembly protein 17 (Cox17), and Cu metabolism MURR1 domain 1 (Commd1) were up-regulated (P ≤ 0.05) in-Cu vs. +Cu fetuses. In conclusion, less expression of duodenal Ctr1 and a tendency for less CTR1 (P = 0.10) and Atp7a (P = 0.08) suggest that Simmentals have a lesser ability to absorb and utilize dietary Cu, and may explain why Simmentals are more prone to Cu deficiency than Angus. Up-regulation of fetal liver Atox1, Cox17, and Commd1 in-Cu fetuses may reflect the great Cu demand by the fetus.}, number={2}, journal={JOURNAL OF ANIMAL SCIENCE}, author={Fry, R. S. and Spears, J. W. and Lloyd, K. E. and O'Nan, A. T. and Ashwell, M. S.}, year={2013}, month={Feb}, pages={861–871} }
 @article{robbins_artuso-ponte_moeser_morrow_spears_gebreyes_2013, title={Effects of quaternary benzo(c)phenanthridine alkaloids on growth performance, shedding of organisms, and gastrointestinal tract integrity in pigs inoculated with multidrug-resistant Salmonella spp}, volume={74}, DOI={10.2460/ajvr.74.12.1530}, abstractNote={Abstract}, number={12}, journal={American Journal of Veterinary Research}, author={Robbins, R. C. and Artuso-Ponte, V. C. and Moeser, A. J. and Morrow, W. E. M. and Spears, J. W. and Gebreyes, W. A.}, year={2013}, pages={1530–1535} }
 @article{fry_ashwell_lloyd_o'nan_flowers_stewart_spears_2012, title={Amount and source of dietary copper affects small intestine morphology, duodenal lipid peroxidation, hepatic oxidative stress, and mRNA expression of hepatic copper regulatory proteins in weanling pigs}, volume={90}, ISSN={["1525-3163"]}, DOI={10.2527/jas.2011-4403}, abstractNote={Thirty weanling, crossbred barrows (SUS SCROFA) were used to determine the effects of amount and source of dietary Cu on small intestinal morphology and lipid peroxidation, Cu metabolism, and mRNA expression of proteins involved in hepatic Cu homeostasis. At 21 d of age, pigs were stratified by BW (6.33 ± 0.23 kg) and allocated to 1 of the following dietary treatments: i) control (no supplemental Cu; 6.7 mg Cu/kg), ii) 225 mg supplemental Cu/kg diet from Cu sulfate (CuSO(4)), or iii) 225 mg supplemental Cu/kg diet from tribasic Cu chloride (TBCC). Pigs were housed 2 pigs per pen and were fed a 3-phase diet regimen until d 35 or 36 of the study. During harvest, bile and liver were obtained for mineral analysis, and liver samples were also obtained for analysis of liver glutathione (GSH) and mRNA expression of Cu regulatory proteins. Segments of duodenum, proximal jejunum, and ileum were obtained for mucosal morphology, and duodenal mucosal scrapings were collected from all pigs for analysis of malondialdehyde (MDA). Duodenal villus height was reduced in CuSO(4) pigs compared with control (P = 0.001) and TBCC (P = 0.03) pigs. Villus height in the proximal jejunum of CuSO(4) pigs was reduced (P = 0.03) compared with control pigs, but ileal villus height was not affected (P = 0.82) by treatment. Duodenal MDA concentrations were greater (P = 0.03) in CuSO(4) pigs and tended to be greater (P = 0.10) in pigs supplemented with TBCC compared with control pigs. Liver Cu was greater (P = 0.01) in CuSO(4) vs. control pigs, and tended (P = 0.07) to be greater in TBCC pigs than control pigs. Bile Cu concentrations were greater (P < 0.001) in CuSO(4) and TBCC pigs vs. controls and were also greater (P = 0.04) in TBCC vs. CuSO(4) pigs. Total liver GSH concentrations were less (P = 0.02) in pigs fed diets supplemented with CuSO(4) vs. pigs fed control diets but total liver GSH did not differ (P = 0.11) between control and TBCC pigs. Hepatic mRNA of cytochrome c oxidase assembly protein 17 was less (P = 0.01) in CuSO(4) and tended to be less (P = 0.08) in TBCC pigs vs. control pigs. Expression of antioxidant 1 mRNA was greater (P = 0.04) in TBCC pigs and tended to be greater (P = 0.06) in CuSO(4) pigs compared with control pigs. Results of this study indicated that, when fed at 225 mg Cu/kg diet, TBCC may cause less oxidative stress in the duodenum than CuSO(4). Feeding weanling pigs increased Cu resulted in modulation of certain Cu transporters and chaperones at the transcription level.}, number={9}, journal={JOURNAL OF ANIMAL SCIENCE}, author={Fry, R. S. and Ashwell, M. S. and Lloyd, K. E. and O'Nan, A. T. and Flowers, W. L. and Stewart, K. R. and Spears, J. W.}, year={2012}, month={Sep}, pages={3112–3119} }
 @article{spears_whisnant_huntington_lloyd_fry_krafka_lamptey_hyda_2012, title={Chromium propionate enhances insulin sensitivity in growing cattle}, volume={95}, ISSN={["1525-3198"]}, DOI={10.3168/jds.2011-4845}, abstractNote={Thirty-six Angus and Angus×Simmental heifers, averaging 291 kg, were used to determine the effects of dietary Cr, in the form of Cr propionate (Cr Prop), on glucose metabolism and serum insulin concentrations following glucose administration. Heifers were stratified by body weight (BW) within a breed and randomly assigned to treatments. Treatments consisted of 0, 3, 6, or 9 mg of supplemental Cr/d from Cr Prop. Based on dry matter (DM) intakes, the daily doses of Cr were equivalent to 0.47, 0.94, and 1.42 mg of supplemental Cr/kg of DM. Heifers were individually fed a corn silage-based diet at a level of 2% of BW. Each heifer was also fed 0.45 kg of a ground corn supplement daily that served as a carrier for supplemental Cr. Glucose tolerance tests were performed on d 44 of the study. Glucose was infused via jugular catheters at a level of 0.45 g/kg of BW(0.75) over a course of 1 to 2 min. Blood samples were collected at -10, 0, 5, 10, 15, 30, 45, 60, 90, 120, 150, and 180 min relative to glucose dosing for glucose and insulin determination. Area under the glucose response curve was lower (1,603 vs. 1,964 mg/dL per minute) in heifers supplemented with Cr from 0 to 45 min following glucose challenge. Serum insulin concentrations were lower in Cr-supplemented heifers than in controls following glucose infusion. The molar ratio of insulin to glucose was also lower in Cr-supplemented heifers relative to controls. Serum insulin and serum insulin to glucose ratios did not differ among heifers supplemented with 3, 6, or 9 mg of Cr/d. Results indicate that Cr Prop supplementation increased tissue sensitivity to insulin in growing heifers. Based on insulin sensitivity, Cr requirements (as Cr Prop) of growing heifers can be met by supplementing with 3 mg of Cr/d or 0.47 mg of Cr/kg of DM.}, number={4}, journal={JOURNAL OF DAIRY SCIENCE}, author={Spears, J. W. and Whisnant, C. S. and Huntington, G. B. and Lloyd, K. E. and Fry, R. S. and Krafka, K. and Lamptey, A. and Hyda, J.}, year={2012}, month={Apr}, pages={2037–2045} }
 @article{brooks_grimes_lloyd_valdez_spears_2012, title={Relative bioavailability in chicks of manganese from manganese propionate}, volume={21}, ISSN={["1537-0437"]}, DOI={10.3382/japr.2011-00331}, abstractNote={SUMMARY The relative bioavailability (RB) of Mn propionate, as compared with feed-grade Mn sulfate, was determined in chicks fed a corn- and soybean meal-based diet for 14 d. Diets were supplemented with 0, 20, 100, and 500 mg of Mn/kg of diet and assessed for growth, intake, and FE. Levels of Ca and P were also increased in this diet compared with a typical production diet to see whether, when chicks were challenged with antagonists, a difference existed between inorganic Mn sulfate and organic Mn propionate. No differences were observed for any growth parameters for either mineral level or dietary source. Relative bioavailability was determined using Mn concentration in bone, assuming a value of 100% from the feed-grade Mn sulfate. The RB of Mn propionate was 139% compared with Mn sulfate when using the relative slope assay. We concluded that organic Mn propionate has an improved RB compared with the commonly used inorganic feed-grade Mn sulfate in the presence of high dietary Ca and P.}, number={1}, journal={JOURNAL OF APPLIED POULTRY RESEARCH}, author={Brooks, M. A. and Grimes, J. L. and Lloyd, K. E. and Valdez, F. and Spears, J. W.}, year={2012}, month={Mar}, pages={126–130} }
 @article{fry_brown_lloyd_hansen_legleiter_robarge_spears_2011, title={Effect of dietary boron on physiological responses in growing steers inoculated with bovine herpesvirus type-1}, volume={90}, ISSN={["1532-2661"]}, DOI={10.1016/j.rvsc.2010.04.016}, abstractNote={Thirty-six Angus and Angus × Simmental steers were fed one of three dietary treatments; (1) control (no supplemental B), (2) 5 mg supplemental B/kg, and (3) 15 mg supplemental B/kg for 47 days to determine the effects of dietary boron (B) on disease resistance following an inoculation with bovine herpesvirus type-1 (BHV-1). On day 34 of the study steers were inoculated intranasally with BHV-1. Rectal temperatures began to elevate at day 2, and plasma tumor necrosis factor-α concentrations increased (P < 0.05) by day 2 following BHV-1 inoculation. Plasma acute phase proteins were increased (P < 0.01) while plasma interferon-γ was decreased (P < 0.05) by day 4 post-inoculation. Supplementation of B increased (P < 0.001) plasma B concentrations in a dose-responsive manner. However, dietary B did not affect the duration and severity of clinical signs of BHV-1 and had minimal effects on plasma acute phase proteins and cytokines.}, number={1}, journal={RESEARCH IN VETERINARY SCIENCE}, author={Fry, R. S. and Brown, T. T., Jr. and Lloyd, K. E. and Hansen, S. L. and Legleiter, L. R. and Robarge, W. P. and Spears, J. W.}, year={2011}, month={Feb}, pages={78–83} }
 @article{ashwell_fry_spears_o'nan_maltecca_2011, title={Investigation of breed and sex effects on cytochrome P450 gene expression in cattle liver}, volume={90}, ISSN={["0034-5288"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-79951771053&partnerID=MN8TOARS}, DOI={10.1016/j.rvsc.2010.05.029}, abstractNote={Many cytochrome P450 enzymes are involved in xenobiotic metabolism and elimination. In humans, genetic variation in some of these enzymes contributes to inter-individual drug responses, sometimes having significant clinical effects. Transcript levels of eight P450 genes were evaluated in liver to investigate potential differences in breed and sex in cattle. In Angus calves, heifers appeared to have higher gene expression than steers for two of the eight genes. In Angus and Simmental pregnant cows, Angus appeared to have higher gene expression for three of the eight genes. Transcript evaluation is just the first step toward determining if differences exist between breeds and sexes in enzyme catalytic activity. However, others (Giantin et al., 2008) have shown correlations between transcript levels and catalytic activity in other cattle breeds. Therefore breed and/or sex of an animal may need to be considered before administering a dose of a xenobiotic due to the potential for harmful drug residues in foodstuffs as well as improper treatment of disease conditions.}, number={2}, journal={RESEARCH IN VETERINARY SCIENCE}, author={Ashwell, M. S. and Fry, R. S. and Spears, J. W. and O'Nan, A. T. and Maltecca, C.}, year={2011}, month={Apr}, pages={235–237} }
 @article{spears_lloyd_fry_2011, title={Tolerance of cattle to increased dietary sulfur and effect of dietary cation-anion balance}, volume={89}, ISSN={["1525-3163"]}, DOI={10.2527/jas.2010-3265}, abstractNote={The objective of this study was to determine if dietary cation-anion balance (DCAB) affects the concentration of S that can be tolerated by growing and finishing cattle without adversely affecting performance. Angus cross and Bradford steers (n=114; average initial BW=252.8 kg) were blocked by BW and breed, and randomly assigned within a block to treatment. The design was a 3 × 2 factorial arrangement of treatments with S (from NH(4)SO(4)) supplemented at 0, 0.15, or 0.30% of DM, and NaHCO(3) added at 0 or 1.0% of DM. Each treatment consisted of 3 pens containing 5 steers and 1 pen containing 4 steers. Steers were used in an 84-d growing study followed by a finishing study. A corn silage-based diet was fed during the growing study and a corn-based diet was fed during the finishing study. Steers were not randomized between experiments. The analyzed concentrations of S in the growing diets were 0.12, 0.30, and 0.46%, whereas the analyzed concentrations of S in the finishing diets were 0.13, 0.31, and 0.46% for treatments supplemented with 0, 0.15, and 0.30% S, respectively. Increasing DCAB by approximately 15 mEq/100 g of DM, by the addition of NaHCO(3,) did not affect (P > 0.36) performance during the growing or finishing studies. During the growing study DMI was not affected (P=0.29) by dietary S. Steers fed diets containing 0.30% S had greater ADG (P=0.02) and G:F (P=0.01) than those receiving 0.46% S, but similar (P > 0.36) performance to steers fed 0.12% S. During the finishing study, steers fed diets containing 0.46% S had less ADG than steers fed 0.13 (P=0.004) or 0.31% S (P=0.07), whereas ADG did not differ (P=0.18) among steers fed 0.13 and 0.31% S. Steers fed diets containing 0.31 (P=0.01) or 0.46% S (P=0.001) had less DMI than controls, but G:F was not affected (P=0.52) by S during the finishing study. Carcass characteristics did not differ (P > 0.18) among steers fed diets containing 0.13 and 0.31% S. Steers receiving diets containing 0.46% S had decreased HCW (P=0.001), quality (P=0.02), and yield grades (P=0.04) than steers receiving 0.13% S. Plasma Cu concentrations on d 101 of the finishing phase and liver Cu concentrations at slaughter were greater (P ≤ 0.05) in control steers compared with those fed diets containing 0.31 or 0.46% S. This study indicates that steers fed growing diets can tolerate up to 0.46% S with minimum effects on performance. Finishing steers tolerated diets containing 0.31% S without adverse affects on ADG or G:F. However, 0.46% S greatly decreased ADG and DMI, and increasing DCAB did not prevent these depressions.}, number={8}, journal={JOURNAL OF ANIMAL SCIENCE}, author={Spears, J. W. and Lloyd, K. E. and Fry, R. S.}, year={2011}, month={Aug}, pages={2502–2509} }
 @article{hansen_trakooljul_spears_liu_2010, title={Age and Dietary Iron Affect Expression of Genes Involved in Iron Acquisition and Homeostasis in Young Pigs}, volume={140}, ISSN={["1541-6100"]}, DOI={10.3945/jn.109.112722}, abstractNote={To investigate the effects of dietary iron (Fe) and age on Fe metabolism, we used 36 weaned barrows in a 2 x 3 design with 2 concentrations of dietary Fe [97 (control) and 797 (high Fe) mg Fe/kg dry matter] and 3 time points of tissue collection (after 21, 42, or 63 d on diets). Pigs were weighed and bled on d 0, 20, 41, and 62. High Fe reduced feed efficiency but did not affect pig weight gain. Blood hemoglobin concentrations and Fe concentrations of liver, intestine, and heart were increased by high dietary Fe on all days. Concentrations of liver and heart Fe increased with age. As determined by quantitative real-time PCR, hepatic expression of hepcidin (HAMP) in pigs given the high-Fe diet was 6.25-fold that of control pigs. In the intestine, relative mRNA levels of ferroportin, divalent metal transporter 1, and transferrin receptor were downregulated by high Fe. Expression of an alternative route of Fe absorption, solute carrier family 39 member 14 (SLC39A14), was downregulated in the intestine of pigs fed high dietary Fe. Additionally, duodenal mRNA level of certain genes including scavenger receptor class A, member 5, and frataxin decreased with age of the animal. Our findings indicate new roles in Fe metabolism for several mineral metabolism-associated genes and that some of these genes, such as SLC39A14, may be regulated in response to dietary Fe in pigs. Additionally, the expression of some genes examined in this study was affected by age, suggesting age dependency of Fe metabolism in pigs.}, number={2}, journal={JOURNAL OF NUTRITION}, author={Hansen, Stephanie L. and Trakooljul, Nares and Spears, Jerry W. and Liu, Hsiao-Ching}, year={2010}, month={Feb}, pages={271–277} }
 @article{nose_wood_kim_prohaska_fry_spears_thiele_2010, title={Ctr1 Is an Apical Copper Transporter in Mammalian Intestinal Epithelial Cells in Vivo That Is Controlled at the Level of Protein Stability}, volume={285}, ISSN={["1083-351X"]}, DOI={10.1074/jbc.m110.143826}, abstractNote={Copper is an essential trace element that functions in a diverse array of biochemical processes that include mitochondrial respiration, neurotransmitter biogenesis, connective tissue maturation, and reactive oxygen chemistry. The Ctr1 protein is a high-affinity Cu+ importer that is structurally and functionally conserved in yeast, plants, fruit flies, and humans and that, in all of these organisms, is localized to the plasma membrane and intracellular vesicles. Although intestinal epithelial cell-specific deletion of Ctr1 in mice demonstrated a critical role for Ctr1 in dietary copper absorption, some controversy exists over the localization of Ctr1 in intestinal epithelial cells in vivo. In this work, we assess the localization of Ctr1 in intestinal epithelial cells through two independent mechanisms. Using immunohistochemistry, we demonstrate that Ctr1 localizes to the apical membrane in intestinal epithelial cells of the mouse, rat, and pig. Moreover, biotinylation of intestinal luminal proteins from mice fed a control or a copper-deficient diet showed elevated levels of both total and apical membrane Ctr1 protein in response to transient dietary copper limitation. Experiments in cultured HEK293T cells demonstrated that alterations in the levels of the glycosylated form of Ctr1 in response to copper availability were a time-dependent, copper-specific posttranslational response. Taken together, these results demonstrate apical localization of Ctr1 in intestinal epithelia across three mammalian species and suggest that increased Ctr1 apical localization in response to dietary copper limitation may represent an adaptive response to homeostatically modulate Ctr1 availability at the site of intestinal copper absorption.}, number={42}, journal={JOURNAL OF BIOLOGICAL CHEMISTRY}, author={Nose, Yasuhiro and Wood, L. Kent and Kim, Byung-Eun and Prohaska, Joseph R. and Fry, Robert S. and Spears, Jerry W. and Thiele, Dennis J.}, year={2010}, month={Oct}, pages={32385–32392} }
 @article{fry_lloyd_jacobi_siciliano_robarge_spears_2010, title={Effect of dietary boron on immune function in growing beef steers*}, volume={94}, ISSN={["0931-2439"]}, DOI={10.1111/j.1439-0396.2008.00906.x}, abstractNote={Summary}, number={3}, journal={JOURNAL OF ANIMAL PHYSIOLOGY AND ANIMAL NUTRITION}, author={Fry, R. S. and Lloyd, K. E. and Jacobi, S. K. and Siciliano, P. D. and Robarge, W. P. and Spears, J. W.}, year={2010}, month={Jun}, pages={273–279} }
 @article{lloyd_fellner_mcleod_fry_krafka_lamptey_spears_2010, title={Effects of supplementing dairy cows with chromium propionate on milk and tissue chromium concentrations}, volume={93}, ISSN={["1525-3198"]}, DOI={10.3168/jds.2010-3198}, abstractNote={Eight primiparous and 8 multiparous Holstein cows were used to determine the effects of Cr supplementation, in the form of Cr propionate (Cr Prop), on milk and tissue Cr concentrations. Cows were randomly assigned by parity to one of 2 diets: 1) control diet or 2) 2 mg of supplemental Cr/kg of DM. The level of Cr Prop supplemented exceeded by 4-fold the concentration of 0.5 mg of Cr/kg permitted by the FDA. Experimental diets were fed from approximately 30 d prepartum until at least 91 d postpartum, resulting in a minimum of 121 d of exposure to supplemental Cr. The control prepartum and postpartum diets analyzed 0.48 and 0.38 mg of Cr/kg of DM, respectively. Milk samples were obtained from the a.m. milking on d 0 (colostrum), 7, 14, 21, 28, 42, 56, 77, and 90 and on the final day of the study for Cr analysis. Cows were harvested after lactating for a minimum of 91 d and samples of liver, kidney, semitendinosus muscle, and fat were obtained for Cr analysis. Chromium was measured using electrothermal atomic absorption spectrophotometry. Milk Cr concentration averaged 1.7 ng/mL and was affected by day of lactation but not by Cr or a Cr × day interaction. Supplementation of 2 mg of Cr/kg of DM increased kidney Cr by approximately 3-fold and liver Cr concentrations by approximately 2-fold. Chromium concentrations in muscle and fat were not affected by Cr supplementation. In summary, supplementation of Cr Prop at a level of 2 mg of Cr/kg of DM did not affect Cr concentration in milk, muscle, or fat, the major bovine products consumed by humans.}, number={10}, journal={JOURNAL OF DAIRY SCIENCE}, author={Lloyd, K. E. and Fellner, V. and McLeod, S. J. and Fry, R. S. and Krafka, K. and Lamptey, A. and Spears, J. W.}, year={2010}, month={Oct}, pages={4774–4780} }
 @article{sexson_wagner_engle_spears_2010, title={Effects of water quality and dietary potassium on performance and carcass characteristics of yearling steers}, volume={88}, ISSN={["1525-3163"]}, DOI={10.2527/jas.2009-1899}, abstractNote={Four hundred thirty-two crossbred yearling steers (339 kg +/- 4.8) were used to investigate the effects of water quality and dietary potassium concentration and source on feedlot performance and carcass merit. The study was conducted using a 2 x 3 factorial treatment arrangement. Factors evaluated included 2 water sources: 1) a blend of reverse osmosis and well water (RO; 608 +/- 164 mg/L of SO(4)) and 2) 100% well water with SO(4) concentration of 1,933 +/- 53 mg/L and 3 dietary K treatments. Potassium treatments included 0.75% K with supplemental K from potassium chloride (0.75% K-KCl), 0.75% K with supplemental K from potassium carbonate (0.75% K-K(2)CO(3)), and 1.0% K with supplemental K from potassium carbonate (1.0% K-K(2)CO(3)). Interactions between water quality and dietary treatments were not significant. Dry matter intake tended (P = 0.10) to be greater for steers consuming RO water compared with well water and was not affected by dietary treatment. Feed efficiency (P = 0.04) and NE(g) recovery (P = 0.04) were greater for 1.0% K-K(2)CO(3) compared with 0.75% K-KCl but were not affected by water quality. Final BW was heavier (P < 0.001) and ADG was greater (P = 0.04) for RO water compared with well water but were not affected by diet. Carcasses from steers that consumed RO water tended (P = 0.08) to be heavier than carcasses from steers consuming well water. Dietary treatment did not affect HCW (P = 0.52). Yield grade calculated from carcass measurements was not affected by dietary treatment or water quality. Carcasses from steers consuming well water had greater (P = 0.04) marbling scores than RO water. These data demonstrate that steers consuming RO water achieved improved feedlot performance. Steers fed 1.0% K-K(2)CO(3) were more efficient and demonstrated improved energy recovery compared with steers fed 0.75% K-KCl. Improved efficiency and energy recovery may be related to a reduction (P = 0.06) in the liver abscess rate for steers consuming 1.0% K-K(2)CO(3). Dietary cation-anion balance was positively related to ADG (P < 0.01) and NE(g) (P = 0.03) recovery but negatively related to marbling score (P = 0.04).}, number={1}, journal={JOURNAL OF ANIMAL SCIENCE}, author={Sexson, J. L. and Wagner, J. J. and Engle, T. E. and Spears, J. W.}, year={2010}, month={Jan}, pages={296–305} }
 @article{hansen_ashwell_moeser_fry_knutson_spears_2010, title={High dietary iron reduces transporters involved in iron and manganese metabolism and increases intestinal permeability in calves}, volume={93}, ISSN={["1525-3198"]}, DOI={10.3168/jds.2009-2341}, abstractNote={A 56-d experiment was designed to examine the effect of high dietary Fe on metal transporters involved in Fe and Mn metabolism. Fourteen weaned Holstein calves were stratified by weight and randomly assigned to 1 of 2 treatments: 1) no supplemental Fe (normal Fe) or 2) 750mg of supplemental Fe/kg of dry matter (high Fe). Jugular blood was collected on d 0, 35, and 56. At the end of the trial, 6 calves per treatment were humanely killed and duodenal scrapings, liver, and heart were collected for analysis. Additionally, proximal duodenum was mounted on Ussing chambers to assess intestinal barrier integrity. Calves receiving high dietary Fe displayed decreased transepithelial resistance and increased apical-to-basolateral flux of radiolabeled mannitol, suggesting that high Fe created increased intestinal permeability. Feeding calves a diet high in Fe decreased average daily gain, dry matter intake, and feed efficiency. Hemoglobin and serum Fe concentrations did not differ due to dietary treatment. High dietary Fe increased concentrations of Fe in the liver, but did not affect heart or duodenal Fe concentrations. Duodenal Mn concentrations were lowered by feeding a high Fe diet, but liver and heart Mn concentrations were not affected. As determined by real-time reverse transcription PCR, relative hepatic expression of the gene that encodes the Fe regulatory hormone hepcidin was 5-fold greater in calves fed high dietary Fe. Hepcidin is released in response to increased Fe status and binds to the Fe export protein ferroportin causing ferroportin to be degraded, thereby reducing dietary Fe absorption. Confirmation of this result was achieved through Western blotting of duodenal protein, which revealed that ferroportin was decreased in calves fed high dietary Fe. Duodenal protein expression of divalent metal transporter 1 (DMT1), a Fe import protein that can also transport Mn, tended to be reduced by high dietary Fe. Transcript levels of several genes involved in Fe metabolism in liver and duodenum were unchanged by treatment. In summary, feeding calves a diet high in Fe induced a signal cascade (hepcidin) designed to reduce absorption of Fe (via reduced protein expression of ferroportin and DMT1) in a manner similar to that reported in rodents. Additionally, reduced levels of DMT1 protein appeared to decrease duodenal Mn, suggesting that Mn may also be a substrate for DMT1 in cattle.}, number={2}, journal={JOURNAL OF DAIRY SCIENCE}, author={Hansen, S. L. and Ashwell, M. S. and Moeser, A. J. and Fry, R. S. and Knutson, M. D. and Spears, J. W.}, year={2010}, month={Feb}, pages={656–665} }
 @article{hansen_trakooljul_liu_hicks_ashwell_spears_2010, title={Proteins involved in iron metabolism in beef cattle are affected by copper deficiency in combination with high dietary manganese, but not by copper deficiency alone}, volume={88}, ISSN={["1525-3163"]}, DOI={10.2527/jas.2009-1846}, abstractNote={A 493-d study was conducted to determine the impact of a severe, long-term Cu deficiency on Fe metabolism in beef cattle. Twenty-one Angus calves were born to cows receiving one of the following treatments: 1) adequate Cu (+Cu), 2) Cu deficient (-Cu), and 3) Cu deficient plus high Mn (-Cu+Mn). Copper deficiency was induced through the addition of 2 mg of Mo/kg of DM. After weaning, calves remained on the same treatment as their dam through growing (basal diet analyzed 7 mg of Cu/kg of DM) and finishing (analyzed 4 mg of Cu/kg of DM) phases. Plasma Fe concentrations were positively correlated (P < 0.01; r = 0.49) with plasma Cu concentrations. Liver Fe concentrations were greater (P = 0.05) in -Cu vs. +Cu calves and further increased (P = 0.07) in -Cu+Mn vs. -Cu calves. There was a negative relationship (P < 0.01; r = -0.31) between liver Cu and Fe concentrations. This relationship is likely explained by less (P < 0.01) plasma ceruloplasmin activity in -Cu than +Cu calves. As determined by real-time reverse transcription-PCR, relative expression of hepatic hepcidin was significantly downregulated (>1.5 fold) in -Cu compared with +Cu calves (P = 0.03), and expression of hepatic ferroportin tended (P = 0.09) to be downregulated in -Cu vs. +Cu. In the duodenum, ferritin tended to be upregulated in -Cu. vs. +Cu calves (P < 0.06). No significant change (P > 0.2) due to Cu-deficiency was detected at the transcriptional level for either isoform of divalent metal transporter 1 (DMT1 mRNA with or without an iron responsive element; dmt1IRE and dmt1-nonIRE) in liver or intestine. Duodenal expression of hephaestin and ferroportin protein was not affected by dietary treatment (P > 0.20). However, duodenal expression of DMT1 protein was less (P = 0.04) in -Cu+Mn steers vs. -Cu steers. In summary, Cu deficiency alone did affect hepatic gene expression of hepcidin and ferroportin, but did not affect duodenal expression of proteins important in Fe metabolism. However, the addition of 500 mg of Mn/kg of DM to a diet low in Cu reduced duodenal expression of the Fe import protein DMT1.}, number={1}, journal={JOURNAL OF ANIMAL SCIENCE}, author={Hansen, S. L. and Trakooljul, N. and Liu, H. -C. S. and Hicks, J. A. and Ashwell, M. S. and Spears, J. W.}, year={2010}, month={Jan}, pages={275–283} }
 @article{hansen_spears_2009, title={Bioaccessibility of iron from soil is increased by silage fermentation}, volume={92}, ISSN={["1525-3198"]}, DOI={10.3168/jds.2008-1933}, abstractNote={High dietary Fe can negatively affect absorption of other minerals and cause tissue damage through the production of free radicals. Cattle are often exposed to high dietary Fe, and soil ingestion may represent a major dietary source of Fe. Iron in soil is often found in the ferric form bound in insoluble complexes; however, exposure to an acidic environment similar to that occurring during silage fermentation may cause this Fe to be reduced to the more soluble ferrous form. To test this theory, a 2 x 2 x 3 factorial arrangement examining time, level, and type of soil addition to greenchop was used. Factors included 2 times of soil addition (before or after ensiling), 2 levels of soil inclusion (1 and 5% contamination, wet basis) and 3 types of soil (Cecil clay loam, 3.4% Fe; Georgeville silt loam, 4.3% Fe; and Dyke clay loam, 6.9% Fe). In addition, greenchop with no soil added was ensiled to serve as a control. Fresh corn greenchop was mixed with the appropriate type and level of soil and tightly packed in experimental silos. Fermentation was allowed to proceed for 90 d before silos were opened and silage was freeze-dried and ground. To simulate contamination after ensiling, each soil type was added to control silage at the 2 levels of inclusion. Addition of soil to greenchop before ensiling resulted in greater amounts of water soluble Fe compared with soil addition after ensiling, suggesting that Fe-soil binding properties were altered by ensiling. To test the potential bioaccessibility of Fe during ruminant digestion, an enzymatic in vitro system was modified to simulate ruminal, abomasal, and intestinal digestion. The presence of soil, regardless of time of addition, type, or inclusion level, resulted in greater soluble or bioaccessible Fe concentrations after all 3 phases when compared with control silage. Ensiling further increased soluble Fe concentrations after each phase when compared with silage contaminated with soil after ensiling. In addition, dialyzable Fe concentration (15,000 Da molecular weight cut off) following intestinal phase simulation was greater due to ensiling. Iron that becomes soluble during the intestinal phase may be available to the animal for absorption, and ensiling resulted in increased concentrations of potentially bioavailable Fe. These results suggest that soil contamination of harvested feeds before ensiling may represent a major source of bioavailable Fe in the diets of cattle.}, number={6}, journal={JOURNAL OF DAIRY SCIENCE}, author={Hansen, S. L. and Spears, J. W.}, year={2009}, month={Jun}, pages={2896–2905} }
 @article{hansen_trakooljul_liu_moeser_spears_2009, title={Iron Transporters Are Differentially Regulated by Dietary Iron, and Modifications Are Associated with Changes in Manganese Metabolism in Young Pigs}, volume={139}, ISSN={["1541-6100"]}, DOI={10.3945/jn.109.105866}, abstractNote={To investigate the effects of dietary iron (Fe) on manganese (Mn) metabolism, 24 weaned pigs (21 d old) were blocked by litter and weight and randomly assigned to the following treatments: 1) no supplemental Fe [low Fe (L-Fe)]; 2) 100 mg supplemental Fe/kg [adequate Fe (A-Fe)]; and 3) 500 mg supplemental Fe/kg [high Fe (H-Fe)]. The basal diet was analyzed to contain 20 mg Fe/kg. Tissues were harvested after 32 d of feeding. Daily gain (least square means +/- SEM) was greater in A-Fe pigs (328.3 +/- 29.9 g/d) than in L-Fe pigs (224.0 +/- 11.2 g/d). Hemoglobin concentrations on d 32 were lower in L-Fe pigs (62 +/- 3.5 g/L) than in A-Fe pigs (128 +/- 5.6 g/L) and did not differ between pigs fed A-Fe and H-Fe (133 +/- 12.0 g/L). Liver Fe increased with increasing dietary Fe. Relative hepatic hepcidin expression was greater in pigs fed A-Fe and H-Fe than in those fed L-Fe. Relative expressions of duodenal divalent metal transporter 1 (DMT1) and solute carrier family 39 member 14 (ZIP14) were increased in L-Fe pigs compared with H-Fe pigs. Liver copper (Cu) was higher in L-Fe (0.56 +/- 0.04 mmol/kg) and H-Fe (0.58 +/- 0.04 mmol/kg) pigs than in A-Fe pigs (0.40 +/- 0.04 mmol/kg). Liver Mn was lower in H-Fe pigs (0.15 +/- 0.01 mmol/kg) than in A-Fe (0.23 +/- 0.02 mmol/kg) or L-Fe pigs (0.20 +/- 0.02 mmol/kg). Duodenal Mn concentrations were greater in L-Fe pigs than in A-Fe or H-Fe pigs. Fe deficiency in pigs increased gene expression of duodenal metal transporters (DMT1 and ZIP14) and supplementation with H-Fe reduced expression of DMT1 and ZIP14, which may have decreased absorption of Mn.}, number={8}, journal={JOURNAL OF NUTRITION}, author={Hansen, Stephanie L. and Trakooljul, Nares and Liu, Hsiao-Ching and Moeser, Adam J. and Spears, Jerry W.}, year={2009}, month={Aug}, pages={1474–1479} }
 @article{hepburn_arthington_hansen_spears_knutson_2009, title={Technical note: Copper chaperone for copper, zinc superoxide dismutase: A potential biomarker for copper status in cattle}, volume={87}, ISSN={["1525-3163"]}, DOI={10.2527/jas.2009-1978}, abstractNote={Copper chaperone for Cu, Zn superoxide dismutase (CCS) has been shown to be reflective of Cu status in mice and rats. The objective of this study was to evaluate liver and erythrocyte CCS as an indicator of Cu status in beef cattle (Exp. 1), and to test the acute-phase properties of CCS under conditions of inflammation (Exp. 2). In Exp. 1, samples of whole blood and liver were collected at slaughter (492 d of age) from 15 Cu-deficient and 6 Cu-adequate Angus calves. At the time of tissue collection, severe Cu deficiency had been achieved and differences (P < 0.0001) in plasma and liver Cu among Cu-adequate and Cu-deficient calves were extreme (1.26 vs. 0.19 mg/L and 208.4 vs. 6.3 mg/kg for plasma and liver Cu, respectively). Protein levels of CCS were greater in liver (40%; P = 0.02) and erythrocytes (65%; P < 0.0001) of Cu-deficient vs. Cu-adequate calves. In Exp. 2, inflammatory responses were elicited in beef heifers by administration of a Mannheimia hemolytica vaccine. Four days after vaccination, plasma concentrations of the Cu-dependent protein ceruloplasmin and the Cu-independent protein haptoglobin were increased (P < 0.001) by 71 and 83%, respectively. In contrast, detection of CCS protein in samples of liver and erythrocytes did not differ (P >or= 0.45) between baseline (d 0) and d 4 after vaccination. These data demonstrate that bovine erythrocyte and liver CCS protein levels increase in Cu-deficient cattle. Furthermore, levels of CCS protein do not change after a vaccine-induced inflammatory response, suggesting that unlike ceruloplasmin, CCS may be a reliable indicator of Cu status in cattle.}, number={12}, journal={JOURNAL OF ANIMAL SCIENCE}, author={Hepburn, J. J. and Arthington, J. D. and Hansen, S. L. and Spears, J. W. and Knutson, M. D.}, year={2009}, month={Dec}, pages={4161–4166} }
 @article{hansen_ashwell_legleiter_fry_lloyd_spears_2009, title={The addition of high manganese to a copper-deficient diet further depresses copper status and growth of cattle}, volume={101}, ISSN={["1475-2662"]}, DOI={10.1017/S0007114508057589}, abstractNote={A study was conducted evaluating the effect of long-term Cu deficiency, with or without high Mn, on growth, gene expression and Cu status of beef cattle. Twenty-one Angus calves were born to cows receiving one of the following treatments: (1) 10 mg supplemental Cu/kg DM (+Cu); (2) no supplemental Cu and 2 mg Mo/kg DM ( − Cu); (3) − Cu diet plus 500 mg supplemental Mn/kg DM ( − Cu+Mn). Calves were weaned at approximately 183 d of age and individually fed throughout the growing and finishing phases. Plasma Cu was lower (P < 0·01) in − Cu calves compared with +Cu calves while high dietary Mn further depressed (P < 0·01) plasma Cu in − Cu+Mn calvesv.− Cu calves. Liver Cu concentrations in +Cu calves were greater (P < 0·01) than in − Cu calves, with no differences between − Cu and − Cu+Mn calves. The daily body-weight gain of +Cu calves was greater (P < 0·01) than − Cu calves during the period from birth to weaning, but did not differ during the growing phase. − Cu+Mn calves gained less (P < 0·05) than − Cu calves during the growing phase. DM intake was lower (P < 0·01) in − Cu+Mn calvesv.− Cu calves, and did not differ among +Cu and − Cu calves. The relative gene expression of cytochrome c oxidase in the liver was lower (P < 0·05) in − Cu calves compared with +Cu or − Cu+Mn calves. In conclusion, feeding a Cu − deficient diet in combination with high Mn negatively affected the growth and Cu status of beef cattle.}, number={7}, journal={BRITISH JOURNAL OF NUTRITION}, author={Hansen, Stephanie L. and Ashwell, Melissa S. and Legleiter, Leon R. and Fry, Robert S. and Lloyd, Karen E. and Spears, Jerry W.}, year={2009}, month={Apr}, pages={1068–1078} }
 @article{hansen_schlegel_legleiter_lloyd_spears_2008, title={Bioavailability of copper from copper glycinate in steers fed high dietary sulfur and molybdenum}, volume={86}, ISSN={["0021-8812"]}, DOI={10.2527/jas.2006-814}, abstractNote={Sixty Angus (n = 29) and Angus-Sim-mental cross (n = 31) steers, averaging 9 mo of age and 277 kg of initial BW, were used in a 148-d study to determine the bioavailability of copper glycinate (CuGly) relative to feed-grade copper sulfate (CuSO(4)) when supplemented to diets high in S and Mo. Steers were blocked by weight within breed and randomly assigned to 1 of 5 treatments: 1) control (no supplemental Cu), 2) 5 mg of Cu/kg of DM from CuSO(4), 3) 10 mg of Cu/kg of DM from CuSO(4), 4) 5 mg of Cu/kg of DM from CuGly, and 5) 10 mg of Cu/kg of DM from CuGly. Steers were individually fed a corn silage-based diet (analyzed 8.2 mg of Cu/kg of DM), and supplemented with 2 mg of Mo/kg of diet DM and 0.15% S for 120 d (phase 1). Steers were then supplemented with 6 mg of Mo/kg of diet DM and 0.15% S for an additional 28 d (phase 2). Average daily gain and G:F were improved by Cu supplementation regardless of source (P = 0.01). Final ceruloplasmin, plasma Cu, and liver Cu values were greater (P < 0.05) in steers fed supplemental Cu compared with controls. Plasma Cu, liver Cu, and ceruloplasmin values were greater (P < 0.05) in steers supplemented with 10 mg of Cu/kg of DM vs. those supplemented with 5 mg of Cu/kg of DM. Based on multiple linear regression of final plasma Cu, liver Cu, and ceruloplasmin values on dietary Cu intake in phase 1 (2 mg of Mo/kg of DM), bioavailability of Cu from CuGly relative to CuSO(4) (100%) was 140 (P = 0.10), 131 (P = 0.12), and 140% (P = 0.01), respectively. Relative bio-availability of Cu from CuGly was greater than from CuSO(4) (P = 0.01; 144, 150, and 157%, based on plasma Cu, liver Cu, and ceruloplasmin, respectively) after supplementation of 6 mg of Mo/kg of DM for 28 d. Results of this study suggest that Cu from CuGly may be more available than CuSO(4) when supplemented to diets high in S and Mo.}, number={1}, journal={JOURNAL OF ANIMAL SCIENCE}, author={Hansen, S. L. and Schlegel, P. and Legleiter, L. R. and Lloyd, K. E. and Spears, J. W.}, year={2008}, month={Jan}, pages={173–179} }
 @article{legleiter_spears_liu_2008, title={Copper deficiency in the young bovine results in dramatic decreases in brain copper concentration but does not alter brain prion protein biology}, volume={86}, ISSN={["0021-8812"]}, DOI={10.2527/jas.2007-0403}, abstractNote={An Mn for Cu substitution on cellular prion proteins (PrP(c)) in the brain that results in biochemical changes to PrP(c) has been implicated in the pathogenesis of transmissible spongiform encephalopathies. Recent research in the mature bovine does not support this theory. The present study tested this hypothesis by using progeny from gestating cows receiving Cu-deficient diets or Cu-deficient diets coupled with high dietary Mn. Copper-adequate cows (n = 39) were assigned randomly to 1 of 3 treatments: 1) control (adequate in Cu and Mn), 2) Cu deficient (-Cu), or 3) Cu deficient plus high dietary Mn (-Cu+Mn). Cows assigned to treatments -Cu and -Cu+Mn received no supplemental Cu and were supplemented with Mo to further induce Cu deficiency. The -Cu+Mn treatment also received 500 mg of supplemental Mn/kg of dietary DM. Calves were weaned at 180 d and maintained on the same treatments as their respective dams for 260 d. Copper-deficient calves (-Cu and -Cu+Mn) had decreased (P = 0.001) brain (obex) Cu and tended to have increased (P = 0.09) obex Mn relative to control calves. Obex Mn:Cu ratios were substantially increased (P < 0.001) in calves receiving -Cu and -Cu+Mn treatments compared with control calves and were greater (P < 0.001) in -Cu+Mn calves than in -Cu calves. Obex prion protein characteristics, including proteinase K degradability, superoxide dismutase (SOD)-like activity, and glycoform distributions, were largely unaffected. Obex tissue antioxidant capacity was not compromised by perturbations in brain metals, but Cu-deficient calves tended to have decreased (P = 0.06) Cu:Zn SOD activity and increased (P = 0.06) Mn SOD activity. Although obex Cu was decreased because of Cu deficiency and Mn increased because of exposure to high dietary Mn, the obex metal imbalance had minimal effects on PrP(c) functional characteristics in the calves.}, number={11}, journal={JOURNAL OF ANIMAL SCIENCE}, author={Legleiter, L. R. and Spears, J. W. and Liu, H. C.}, year={2008}, month={Nov}, pages={3069–3078} }
 @article{plumstead_leytem_maguire_spears_kwanyuen_brake_2008, title={Interaction of calcium and phytate in broiler diets. 1. Effects on apparent prececal digestibility and retention of phosphorus}, volume={87}, ISSN={["1525-3171"]}, DOI={10.3382/ps.2007-00231}, abstractNote={Phytate P utilization from soybean meal (SBM) included in broiler diets has been shown to be poor and highly dependent on dietary Ca intake. However, the effect of Ca on P utilization and on the optimal ratio of Ca to nonphytate P (Ca:NPP) when diets contained varying levels of phytate has not been clearly shown and was the objective of this research. A factorial treatment structure was used with 4 dietary Ca levels from 0.47 to 1.16% and 3 levels of phytate P (0.28, 0.24, and 0.10%). Varying dietary phytate P levels were obtained by utilizing SBM produced from 3 varieties of soybeans with different phytate P concentrations. Ross 508 broiler chicks were fed 1 of 12 diets from 16 to 21 d of age. Excreta were collected from 16 to 17 d and from 19 to 20 d of age and ileal digesta was collected at 21 d of age. Apparent prececal P digestibility decreased when dietary Ca concentration increased and was higher when diets contained low-phytate SBM. The apparent digestibility of Ca and percentage of phytate P hydrolysis at the distal ileum were not reduced when dietary phytate P concentration increased. Including low-phytate SBM in diets reduced total P output in the excreta by 49% compared with conventional SBM. The optimum ratio of Ca:NPP that resulted in the highest P retention and lowest P excretion was 2.53:1, 2.40:1, and 2.34:1 for diets with 0.28, 0.24, and 0.10% phytate P. These data suggested that increased dietary Ca reduced the extent of phytate P hydrolysis and P digestibility and that the optimum Ca:NPP ratio at which P retention was maximized was reduced when diets contained less phytate P.}, number={3}, journal={POULTRY SCIENCE}, author={Plumstead, P. W. and Leytem, A. B. and Maguire, R. O. and Spears, J. W. and Kwanyuen, P. and Brake, J.}, year={2008}, month={Mar}, pages={449–458} }
 @article{spears_weiss_2008, title={Role of antioxidants and trace elements in health and immunity of transition dairy cows}, volume={176}, DOI={10.1016/j.tvj1.2007.12.015}, number={1}, journal={Veterinary Journal}, author={Spears, J. W. and Weiss, W. P.}, year={2008}, pages={70–76} }
 @article{wright_spears_webb_2008, title={Uptake of zinc from zinc sulfate and zinc proteinate by ovine ruminal and omasal epithelia}, volume={86}, ISSN={["0021-8812"]}, DOI={10.2527/jas.2006-650}, abstractNote={Uptake and transport of Zn from (65)Zn-labeled ZnSO(4) and Zn proteinate (ZnProt) by ruminal and omasal epithelia were examined by using a parabiotic chamber system. Uptake was measured during a 4-h incubation with 10, 20, or 200 microM Zn as ZnSO(4) or ZnProt in the mucosal buffer (pH 6.0, Krebs-Ringer phosphate). Zinc uptake and transport were also evaluated after simulated ruminal digestion. Buffered ruminal fluid contained a feed substrate and 10 or 200 microM added Zn as ZnSO(4) or ZnProt. In a preliminary experiment, uptake of Zn by omasal tissue was low; thus, the remaining experiments were conducted solely with ruminal epithelium. Incubations to determine the effect of time on Zn uptake from mucosal buffer containing 20 microM added Zn as ZnSO(4) or ZnProt resulted in increased (P < 0.01) Zn uptake as incubation time increased from 30 to 240 min. Zinc uptake was also greater (P = 0.02) from mucosal buffer containing ZnProt compared with ZnSO(4). Zinc uptake from incubations containing 10 or 200 microM was affected by source x concentration (P = 0.05) and concentration x time (P < 0.01) interactions. With 10 microM Zn, uptake was not influenced by Zn source, whereas when 200 microM Zn was added, Zn uptake from ZnProt was greater than from ZnSO(4). Increasing incubation time resulted in increased Zn uptake with 200 microM Zn in the mucosal buffer; however, with 10 microM Zn, uptake did not change after 30 min. After simulated ruminal fermentation, the proportion of Zn in a soluble form was influenced by a source x concentration interaction (P = 0.03). After 18 h of incubation, the proportion of Zn that was soluble was not different between ZnProt and ZnSO(4) in buffered ruminal fluid that contained 10 microM added Zn, but was greater for ZnProt compared with ZnSO(4) with 200 microM Zn in the incubation. Zinc uptake from the aqueous fractions of simulated ruminal digestions containing 200 microM added Zn was greater (P < 0.01) than from those containing 10 microM added Zn. Zinc transport, based on detection of (65)Zn in serosal buffer, did not occur in any of the experiments. The results of the current experiments suggest that absorption of Zn into the bloodstream does not occur from the ruminant foresto-mach; however, Zn uptake occurs in ruminal tissue and is greater from ZnProt than from ZnSO(4).}, number={6}, journal={JOURNAL OF ANIMAL SCIENCE}, author={Wright, C. L. and Spears, J. W. and Webb, K. E., Jr.}, year={2008}, month={Jun}, pages={1357–1363} }
 @article{legleiter_ahola_engle_spears_2007, title={Decreased brain copper due to copper deficiency has no effect on bovine prion proteins}, volume={352}, ISSN={["1090-2104"]}, DOI={10.1016/j.bbrc.2006.11.108}, abstractNote={Copper (Cu) is believed to be integral in prion biology and the lack of Cu or replacement by other metal ions on prions may be involved in prion diseases. This theory has not been evaluated in the bovine. Thus, mature cows were used to determine the effects of Cu deficiency on brain Cu concentrations and prion functional characteristics. Two Cu states were induced, Cu-adequate (n = 4) and Cu-deficient (n = 4). Copper deficiency resulted in decreased (44%) brain Cu concentrations but had no effect on prion concentrations. Based on Western blot analysis, the molecular weights, glycoform distributions, and elution profiles of brain prions were not affected by Cu status. Importantly, Cu status did not affect prion proteinase degradability as all prions were completely degraded by proteinase K. In conclusion, Cu status affected bovine brain Cu concentrations but had no detectable effects on brain prion protein characteristics.}, number={4}, journal={BIOCHEMICAL AND BIOPHYSICAL RESEARCH COMMUNICATIONS}, author={Legleiter, Leon R. and Ahola, Jason K. and Engle, Terry E. and Spears, Jerry W.}, year={2007}, month={Jan}, pages={884–888} }
 @article{plumstead_romero-sanchez_paton_spears_brake_2007, title={Effects of dietary metabolizable energy and protein on early growth responses of broilers to dietary lysine}, volume={86}, ISSN={["0032-5791"]}, DOI={10.3382/ps.2007-00168}, abstractNote={Two studies evaluated effects of metabolizable energy (ME), digestible Lys (dLys), and amino acid (AA) balance on broiler performance. In experiment 1 diets contained 3 levels of ME (3,000, 3,100, and 3,200 kcal/kg) in combination with 4 levels of dLys (1.05, 1.13, 1.21, and 1.29%). A fixed proportion of dLys relative to CP and key indispensable AA was maintained in graded increments of CP from 21.9 to 26.9%. There was no interaction of ME and dLys for 21 d BW gain or adjusted feed conversion ratio, which improved linearly with dietary dLys. Increasing the dLys or ME had no effect on feed intake, and the linear improvement in performance was attributed to a step-wise increase in dLys when diets contained a balance of AA and CP. Experiment 2 evaluated broiler response to 20 d of age when diets contained graded increments in dLys while maintaining a fixed proportion of dLys relative to CP and indispensable AA (balanced CP), or when dLys was increased in diets by supplementing synthetic l-Lys to 1 of 2 basal diets with 22.0% CP (low CP) or 27.0% CP (high CP) without adjusting concentrations of other AA or CP. The BW gain of broilers fed the low CP diet series followed a quadratic response, and the dLys requirement was estimated to be 1.19 +/- 0.03% (1.30% total Lys). By contrast, BW gain on both the high CP and balanced CP diet series increased linearly. The higher BW gain and continued response to dLys above 1.19% when CP and AA concentrations were increased confirmed that the dLys requirement of broilers was dependent on the dietary CP. When a fixed ratio of dLys to CP was applied and indispensable and dispensable AA were not limiting, broiler BW gain and adjusted feed conversion ratio responded positively to incremental dLys up to at least 1.32% (27.2% CP) and was independent of the dietary ME over a range from 3,000 to 3,200 kcal/kg.}, number={12}, journal={POULTRY SCIENCE}, author={Plumstead, P. W. and Romero-Sanchez, H. and Paton, N. D. and Spears, J. W. and Brake, J.}, year={2007}, month={Dec}, pages={2639–2648} }
 @article{arthington_spears_2007, title={Effects of tribasic copper chloride versus copper sulfate provided in corn- and molasses-based supplements on forage intake and copper status of beef heifers}, volume={85}, ISSN={["0021-8812"]}, DOI={10.2527/jas.2006-518}, abstractNote={The objective of this study was to investigate the effect of supplemental tribasic copper chloride (Cu(2)(OH(3))Cl; TBCC) vs. Cu sulfate (CuSO(4)) on Cu status and voluntary forage DMI in growing heifers. Two 90-d experiments were conducted using 48 non-pregnant, crossbred heifers (24 heifers/experiment; 355 +/- 10.7 and 309 +/- 9.9 kg for Exp. 1 and 2, respectively). In each experiment, 3 supplemental Cu treatments were randomly allocated to heifers in individual pens consisting of (1) 100 mg of Cu/d from CuSO(4), (2) 100 mg of Cu/d from TBCC, or (3) 0 mg of Cu/d. The 2 experiments differed by the form of supplement used to deliver the Cu treatments (corn- vs. molasses-based supplements for Exp. 1 and 2, respectively). Supplements were formulated and fed to provide equivalent amounts of CP and TDN daily but differed in their concentration of the Cu antagonists, Mo (0.70 vs. 1.44 mg/kg), Fe (113 vs. 189 mg/kg), and S (0.18 vs. 0.37%) for corn- and molasses-based supplements, respectively. All heifers were provided free-choice access to ground stargrass (Cynodon spp.) hay. Jugular blood and liver biopsy samples were collected on d 0, 30, 60, and 90 of each experiment. Heifer BW was collected on d 0 and 90. Heifer ADG was not affected by Cu treatment (average = 0.22 +/- 0.11 and 0.44 +/- 0.05 kg for Exp. 1 and 2, respectively; P > 0.20). In Exp. 1, heifers provided supplemental Cu, independent of source, had greater (P < 0.05) liver Cu concentrations on d 60 and 90 compared with heifers provided no supplemental Cu. In Exp. 2, average liver Cu concentrations were greater (P = 0.04) for heifers receiving supplemental Cu compared with heifers receiving no Cu; however, all treatments experienced a decrease in liver Cu concentration over the 90-d treatment period. Plasma ceruloplasmin concentrations did not differ in Exp. 1 (P = 0.83) but were greater (P = 0.04) in Exp. 2 for heifers receiving supplemental Cu compared with heifers receiving no Cu. In Exp. 1, voluntary forage DMI was greater (P < 0.05) for heifers provided supplemental Cu, independent of source, compared with heifers provided no Cu. In contrast, voluntary forage DMI was not affected (P > 0.10) by Cu supplementation in Exp. 2. These data imply that CuSO(4) and TBCC are of similar availability when offered to growing beef heifers in both corn- and molasses-based supplements. However, corn- and molasses-based supplements appear to affect Cu metabolism differently. These impacts may affect voluntary forage DMI in growing beef heifers.}, number={3}, journal={JOURNAL OF ANIMAL SCIENCE}, author={Arthington, J. D. and Spears, J. W.}, year={2007}, month={Mar}, pages={871–876} }
 @article{legleiter_liu_lloyd_hansen_fry_spears_2007, title={Exposure to low dietary copper or low copper coupled with high dietary manganese for one year does not alter brain prion protein characteristics in the mature cow}, volume={85}, ISSN={["0021-8812"]}, DOI={10.2527/jas.2007-0215}, abstractNote={It is now widely accepted that abnormal prion proteins are the likely causative agent in bovine spongiform encephalopathy. Cellular prion proteins (PrP(c)) bind Cu, which appears to be required to maintain functional characteristics of the protein. The replacement of Cu on PrP(c) with Mn has resulted in loss of function and increased protease resistance. Twelve mature cows were used to determine the effects of Cu deficiency, alone and coupled with high dietary Mn, on brain Cu and Mn concentrations and on PrP(c) functional characteristics. Copper-adequate cows were randomly assigned to treatments: 1) control (adequate in Cu and Mn), 2) Cu-deficient (-Cu), and 3) Cu-deficient plus high dietary Mn (-Cu+Mn). Cows assigned to treatments -Cu and -Cu+Mn received no supplemental Cu and were supplemented with Mo to further induce Cu deficiency. After 360 d, Cu-deficient cows (-Cu and -Cu+Mn) tended to have lesser concentrations of Cu (P = 0.09) in the obex region of the brain stem. Brain Mn tended (P = 0.09) to be greater in -Cu+Mn cattle compared with -Cu cattle. Western blots revealed that PrP(c) relative optical densities, proteinase K degradability, elution profiles, molecular weights, and glycoform distributions were not different among treatments. The concentration of PrP(c), as determined by ELISA, was similar across treatment groups. Brain tissue (obex) Mn superoxide dismutase activity was greatest (P = 0.04) in cattle receiving -Cu+Mn, whereas immunopurified PrP(c) had similar superoxide dismutase-like activities among treatments. Immunopurified PrP(c) had similar Cu concentrations across treatments, whereas Mn was undetectable. We concluded that Cu deficiency, coupled with excessive Mn intake, in the bovine may decrease brain Cu and increase brain Mn. Copper deficiency, alone or coupled with high dietary Mn, did not cause detectable alterations in PrP(c) functional characteristics.}, number={11}, journal={JOURNAL OF ANIMAL SCIENCE}, author={Legleiter, L. R. and Liu, H. C. and Lloyd, K. E. and Hansen, S. L. and Fry, R. S. and Spears, J. W.}, year={2007}, month={Nov}, pages={2895–2903} }
 @article{legleiter_spears_2007, title={Plasma diamine oxidase: A biomarker of copper deficiency in the bovine}, volume={85}, ISSN={["1525-3163"]}, DOI={10.2527/jas.2006-841}, abstractNote={This study was designed to test the efficacy of plasma diamine oxidase (DAO) activity as a biomarker of Cu deficiency in the bovine. Angus steers (n = 11) and heifers (n = 17) were assigned to 1 of 3 treatments: 1) control (adequate dietary Cu), 2) Cu-deficient (-Cu), and 3) Cu-deficient plus high dietary Mn (-Cu+Mn), and fed from weaning through finishing. Molybdenum (2 mg/kg of DM) was supplemented to treatments -Cu and -Cu+Mn to induce Cu deficiency via the formation of ruminal thiomolybdates. Samples were collected on 2 sampling dates (d 160 and 190) to determine the efficacy of plasma DAO activity as a biomarker of Cu deficiency. For both sampling dates, liver Cu, plasma Cu, and plasma ceruloplasmin activity indicated that cattle receiving diets designed to induce Cu deficiency (-Cu and -Cu+Mn) were Cu-deficient, with all indices of Cu status lower (P < 0.001) than the control animals. In addition to these traditional indices of Cu status, plasma DAO activity also effectively identified Cu-deficient animals because plasma DAO levels were reduced (P < 0.001) by 2- to 3-fold compared with controls. Correlation analysis indicated that plasma DAO activity was highly correlated to all other indices of Cu status (Pearson R = 0.73 to 0.87). During the growing phase, ADG (P = 0.09) and G:F (P = 0.002) were depressed in Cu-deficient animals compared with controls, whereas cattle performed equally well across all treatments in the finishing phase. The plasma DAO activity assay was precise and reliable based on an intraassay CV of 4.4% and interassay CV of 11.1%. Due to increased variability, freezing and thawing of plasma samples resulted in significant changes in DAO activity relative to fresh plasma DAO activity values. Thus, fresh plasma DAO activity, a relatively simple assay, may serve as an effective tool to diagnose Cu deficiency in the bovine.}, number={9}, journal={JOURNAL OF ANIMAL SCIENCE}, author={Legleiter, L. R. and Spears, J. W.}, year={2007}, month={Sep}, pages={2198–2204} }
 @article{stahlhut_whisnant_lloyd_baird_legleiter_hansen_spears_2006, title={Effect of chromium supplementation and copper status on glucose and lipid metabolism in Angus and Simmental beef cows}, volume={128}, ISSN={["1873-2216"]}, DOI={10.1016/j.anifeedsci.2005.11.002}, abstractNote={Pregnant Angus (n = 83) and Simmental (n = 69) cows were blocked by age into three blocks and then randomly assigned by breed to one of two free choice mineral supplements to determine effects of dietary Cr and Cu status on glucose metabolism and blood metabolites in beef cows. Supplements consisted of: (1) control (no supplemental Cr) and (2) 40 mg Cr/kg of mineral (from Cr picolinate). Mineral supplements were formulated to contain all minerals typically supplemented to cattle diets with the exception of Cu. The study began approximately 75 days prepartum, at which time half of the cows in each treatment received a 25 g Cu oxide needle bolus. Blood was collected from 36 cows on days 28, 58, 97 (approximately 20-day postpartum), 155, 210, and 279 for plasma glucose and non-esterified fatty acid (NEFA) determination. Chromium supplementation reduced (P<0.05) plasma glucose concentrations. Plasma glucose concentrations were also affected by breed × Cu bolus (P<0.05). In non-Cu supplemented cows, plasma glucose levels were higher (P<0.05) in Angus versus Simmental cows. In cows receiving a Cu bolus, plasma glucose levels were similar between breeds. Plasma NEFA concentrations were affected by time (P<0.01), Cr × Cu bolus (P<0.05), Cr × time (P<0.01), and Cr × block (P<0.01). On days 97 and 155, plasma NEFA concentrations were lower (P<0.01) in cows receiving Cr relative to control cows. Chromium supplementation reduced (P<0.01) plasma NEFA concentrations in 2 and 3 and 4 and 5-year-old cows but not in older cows, relative to control cows in those blocks. Chromium supplemented cows had lower (P<0.05) plasma NEFA concentrations than control cows that did not receive a Cu bolus. No differences in plasma NEFA concentrations occurred between treatments in cows that received a Cu bolus. At approximately 1-month prepartum and 1-month postpartum, 12 cows were cannulated in their jugular vein and glucose tolerance tests (GTT) were conducted. Cows used in GTT received 0.15 g of glucose/kg body weight as a 500 g/L dextrose solution. Chromium supplemented cows had lower plasma glucose (P<0.01), serum insulin (P<0.05) and NEFA (P<0.01) concentrations following the GTT conducted prepartum versus control cows. Clearance rates for glucose were not affected by treatment. In the postpartum GTT, plasma glucose was affected by an interaction between Cr supplementation and Cu status, as Cr supplemented cows that received a Cu bolus had higher (P<0.001) plasma glucose after glucose administration than cows not supplemented with Cu. No differences in plasma glucose occurred between control cows regardless of Cu status. Chromium supplemented cows had lower (P<0.05) serum insulin concentrations 10–45 min after glucose administration versus control cows. Results indicate that plasma glucose is lower in cows receiving supplemental Cr, and that an interaction between Cr and Cu status may alter glucose metabolism.}, number={3-4}, journal={ANIMAL FEED SCIENCE AND TECHNOLOGY}, author={Stahlhut, H. S. and Whisnant, C. S. and Lloyd, K. E. and Baird, E. J. and Legleiter, L. R. and Hansen, S. L. and Spears, J. W.}, year={2006}, month={Jun}, pages={253–265} }
 @article{stahlhut_whisnant_spears_2006, title={Effect of chromium supplementation and copper status on performance and reproduction of beef cows}, volume={128}, ISSN={["1873-2216"]}, DOI={10.1016/j.anifeedsci.2005.11.003}, abstractNote={Pregnant Angus (n = 83) and Simmental (n = 69) cows were blocked by age into three age blocks and then randomly assigned by breed within a block to one of two free choice mineral supplements to determine effects of dietary Cr and Cu status on performance and reproduction of beef cows. Supplements consisted of: (1) control (no supplemental Cr) and (2) 40 mg Cr/kg of mineral (from Cr picolinate). Mineral supplements were formulated to contain all minerals typically supplemented to cattle diets with the exception of Cu. The study began approximately 75 days prepartum, at which time half of the cows in each treatment received a 25 g Cu oxide needle bolus. Blood was collected from 36 cows on days 0, 28, 58, 97 (approximately 20 days postpartum), 155, 210, and 279, and from 36 calves on days 196 and 279 for plasma Cu determination. Liver biopsies were taken on days 0 and 279 to determine initial and final liver Cu concentrations in cows. Plasma Cu concentrations were affected by Cu bolus × time (P < 0.05), breed × time (P < 0.01), and breed × bolus (P < 0.01) interactions in cows, and by a treatment × time interaction (P < 0.05) in calves. Liver Cu concentrations were affected by breed × time (P < 0.01) and Cu bolus × time (P < 0.05) in cows. Cows receiving a Cu bolus had higher (P < 0.05) plasma Cu on day 97, and higher (P < 0.05) liver Cu on day 279 relative to cows that did not receive a bolus. Simmental cows had lower (P < 0.01) plasma Cu at day 28 and at subsequent sampling days, and lower (P < 0.01) liver Cu on days 0 and 279 than Angus cows. Simmental cows that received a Cu bolus had higher (P < 0.01) plasma Cu concentrations than Simmentals that did not receive supplemental Cu. Supplemental Cr resulted in higher (P < 0.05) plasma Cu concentrations in calves on day 279 versus controls. Overall body weight loss and body weight loss postpartum in cows was affected by breed (P < 0.05) and treatment × block (P < 0.01). Overall and postpartum body weight loss was lower in Angus cows (P < 0.05). Chromium supplementation reduced (P < 0.01) overall and postpartum body weight loss in 2 and 3 years old cows, but not in older cows. Cows supplemented with Cr tended (P < 0.06) to have higher pregnancy rates than controls. Calf birth weights and weaning weights were not affected by Cr or Cu bolus. Results indicate that Cr supplementation may improve fertility and decrease postpartum body weight loss especially in young beef cows.}, number={3-4}, journal={ANIMAL FEED SCIENCE AND TECHNOLOGY}, author={Stahlhut, H. S. and Whisnant, C. S. and Spears, J. W.}, year={2006}, month={Jun}, pages={266–275} }
 @article{huntington_harmon_kristensen_hanson_spears_2006, title={Effects of a slow-release urea source on absorption of ammonia and endogenous production of urea by cattle}, volume={130}, ISSN={["0377-8401"]}, DOI={10.1016/j.anifeedsci.2006.01.012}, abstractNote={Three experiments were conducted with Angus or Holstein steers to evaluate effects of dietary urea–calcium (a slow rumen-release urea source) on absorption of ammonia N from the gut and urea N production in the liver. Steers were fed a high-grain diet (Experiment 1) or an all-forage diet (Experiments 2 and 3). Urea or urea–calcium (0.25 g/kg body weight) was dosed into the esophagus (Experiments 1 and 2) or rumen (Experiment 3), and blood samples were serially collected for 180 min. Blood concentrations of ammonia N and urea N were measured in all experiments, and net flux of metabolites across splanchnic tissues was measured in Experiment 3. Compared to urea, urea–calcium reduced (P<0.05) plasma concentrations of ammonia N in steers fed all-forage diets, and tended (P<0.06) to reduce arterial glucose concentrations in Experiment 3. Plasma concentrations of urea N were not affected by treatment in any experiment. Treatment and time post-dosing interactions (P<0.05) in Experiment 3 were due to increased ruminal fluid concentrations of ammonia N, net release of ammonia N by portal-drained viscera and total splanchnic tissues with urea versus urea–calcium treatment shortly after dosing. Similar interactions (P<0.05) indicated that urea caused higher hepatic glucose release and increased l-lactate release by total splanchnic tissues after dosing than urea–calcium. Urea–calcium was effective in mitigating rapid ammonia release in the rumen and subsequent effects on glucose and lactate metabolism.}, number={3-4}, journal={ANIMAL FEED SCIENCE AND TECHNOLOGY}, author={Huntington, G. B. and Harmon, D. L. and Kristensen, N. B. and Hanson, K. C. and Spears, J. W.}, year={2006}, month={Nov}, pages={225–241} }
 @article{hansen_spears_lloyd_whisnant_2006, title={Feeding a low manganese diet to heifers during gestation impairs fetal growth and development}, volume={89}, ISSN={["0022-0302"]}, DOI={10.3168/jds.S0022-0302(06)72477-8}, abstractNote={A study was conducted to examine the effects of low dietary Mn on growth performance of pregnant heifers and fetal development of their offspring. Twenty pregnant Angus (n = 9) and Simmental (n = 11) heifers averaging 17 mo of age and 447.6 kg of initial body weight were used in the 267-d study. Heifers were selected from a previous study examining the effects of supplemental Mn on growth and reproductive performance of heifers. Ten pregnant heifers per treatment from the control (analyzed at 15.8 mg of Mn/kg of DM) and supplemental Mn (50 mg/kg of DM) treatments were randomly selected at the conclusion of the previous study to continue on their respective dietary treatments through gestation and early lactation. Serum cholesterol for the 267-d period was not affected by treatment. Whole-blood Mn concentration of heifers on d 267 was not affected by treatment. Whole-blood Mn concentration at birth was lower in calves born to control heifers than in those born to supplemented heifers. Calves born to control heifers weighed less at birth than those born to heifers receiving supplemental Mn. Calves born to control heifers suffered from varying signs of Mn deficiency, including superior brachygnathism, unsteadiness, disproportionate dwarfism, and swollen joints. Results suggest that feeding gestating heifers a diet containing 16.6 mg of Mn/kg of DM is not adequate for proper fetal development. Supplementation of 50 mg of Mn/kg of DM to the control diet was sufficient to overcome any signs of Mn deficiency in calves.}, number={11}, journal={JOURNAL OF DAIRY SCIENCE}, author={Hansen, S. L. and Spears, J. W. and Lloyd, K. E. and Whisnant, C. S.}, year={2006}, month={Nov}, pages={4305–4311} }
 @article{hansen_spears_lloyd_whisnant_2006, title={Growth, reproductive performance, and manganese status of heifers fed varying concentrations of manganese}, volume={84}, ISSN={["0021-8812"]}, DOI={10.2527/jas.2005-667}, abstractNote={An experiment was conducted to examine the effects of dietary Mn on growth, reproductive performance, and Mn status of beef heifers. Eighty Angus (n = 40) and Simmental (n = 40) heifers, averaging 249 kg, were stratified by BW within a breed and randomly assigned to 1 of 4 treatments providing 0 (control), 10, 30, or 50 mg of supplemental Mn/kg of DM from MnSO(4). Heifers were individually fed a diet containing cottonseed hulls, corn gluten feed, citrus pulp, and ground corn, and the control diet contained 15.8 mg of Mn/kg of DM by analysis. Average daily gain, DMI, and G:F for the 196-d period were not affected by Mn supplementation. Control heifers had reduced (P = 0.04) liver Mn when contrasted with the 3 levels of supplemental Mn. Serum cholesterol was greater (P = 0.001) in Angus compared with Simmental heifers over the course of the 196-d experiment but was not affected by treatment. Dietary Mn did not significantly affect measures of reproductive performance. Results of this study indicate that 15.8 mg of Mn/kg of diet DM should be adequate for growth, onset of estrus, and conception of beef heifers.}, number={12}, journal={JOURNAL OF ANIMAL SCIENCE}, author={Hansen, S. L. and Spears, J. W. and Lloyd, K. E. and Whisnant, C. S.}, year={2006}, month={Dec}, pages={3375–3380} }
 @article{tiffany_fellner_spears_2006, title={Influence of cobalt concentration on vitamin B-12 production and fermentation of mixed ruminal microorganisms grown in continuous culture flow-through fermentors}, volume={84}, ISSN={["1525-3163"]}, DOI={10.2527/2006.843635x}, abstractNote={An experiment was conducted to determine the effects of dietary concentrations of Co on vitamin B12 production and fermentation of mixed ruminal microbes grown in continuous culture fermentors. Four fermentors were fed 14 g of DM/d. The DM consisted of a corn and cottonseed hull-based diet with Co supplemented as CoCO3. Dietary treatments were 1) control (containing 0.05 mg of Co/kg of DM), 2) 0.05 mg of supplemental Co/kg of DM, 3) 0.10 mg of supplemental Co/kg of DM, and 4) 1.0 mg of supplemental Co/kg of DM. After a 3-d adjustment period, fermentors were sampled over a 3-d sampling period. This process was repeated 2 additional times for a total of 3 runs. Ruminal fluid vitamin B12 concentrations were affected by Co supplementation (P < 0.01), and there was a treatment x day interaction (P < 0.01). By sampling d 3, cultures fed the basal diet supplemented with 0.10 mg of Co/kg had greater (P < 0.05) vitamin B12 concentrations than those supplemented with 0.05 mg of Co/kg of DM, and increasing supplemental Co from 0.10 to 1.0 mg/kg of DM increased (P < 0.01) ruminal fluid vitamin B12 concentration. Ruminal fluid succinate also was affected (P < 0.10) by a treatment x day interaction. Cobalt supplementation to the control diet greatly decreased (P < 0.05) succinate in ruminal cultures on sampling d 3 but not on d 1 or 2. Molar proportions of acetate, propionate, and isobutyrate, and acetate:propionate were not affected by the addition of supplemental Co to the basal diet. However, molar proportions of butyrate, valerate, and isovalerate increased (P < 0.05) in response to supplemental Co. The majority of long-chain fatty acids observed in this study were not affected by Co supplementation. However, percentages of C18:0 fatty acids in ruminal cultures tended (P < 0.10) to be greater for Co-supplemented diets relative to the control. Methane, ammonia, and pH were not greatly affected by Co supplementation. The results indicate that a total (diet plus supplemental) Co concentration of 0.10 to 0.15 mg/kg of dietary DM resulted in adequate vitamin B12 production to meet the requirements of ruminal microorganisms fed a high-concentrate diet in continuous-flow fermentors.}, number={3}, journal={JOURNAL OF ANIMAL SCIENCE}, author={Tiffany, ME and Fellner, V and Spears, JW}, year={2006}, month={Mar}, pages={635–640} }
 @article{tiffany_spears_2005, title={Differential responses to dietary cobalt in finishing steers fed corn-versus barley-based diets}, volume={83}, DOI={10.2527/2005.83112580x}, abstractNote={An experiment was conducted to determine the effects of dietary Co concentration on performance, carcass traits, and plasma, liver, and ruminal metabolites of steers fed corn- or barley-based diets. Sixty steers, initially averaging 316 kg, were stratified by BW and assigned randomly to treatments in a 2 x 3 factorial arrangement, with factors being a corn- or barley-based diet and supplemental Co added at 0, 0.05, or 0.15 mg/kg of DM. Control corn-and barley-based diets analyzed 0.04 and 0.02 mg of Co/kg of DM, respectively. Steers were fed individually using electronic Ca-lan gate feeders. Cobalt supplementation increased (P < 0.05) DMI and ADG over the total study. From d 85 to finish, Co supplementation increased (P < 0.05) ADG by steers fed corn- but not barley-based diets. The G:F was increased (P < 0.05) by Co supplementation during the first 84 d but not over the entire finishing period. Average daily gain and G:F were greater (P < 0.05) for corn- vs. barley-fed steers. Supplemental Co increased vitamin B12 in plasma and liver (P < 0.05), and plasma vitamin B12 was greater (P < 0.05) in steers fed corn-vs. barley-based diets. Cobalt supplementation increased (P < 0.05) ruminal fluid vitamin B12 on d 84 in steers fed corn- but not barley-based diets. Folate was greater in plasma (P < 0.01) and liver (P < 0.05) of steers fed Co-supplemented diets. Increasing supplemental Co from 0.05 to 0.15 mg of Co/kg of DM increased (P < 0.05) liver folate in steers fed barley- but not corn-based diets. Supplemental Co decreased (P < 0.01) plasma methylmalonic acid concentration in steers. Increasing supplemental Co from 0.05 to 0.15 mg/kg of DM decreased plasma and ruminal succinate concentrations, and steers fed barley-based diets had greater (P < 0.05) plasma and ruminal succinate relative to those fed corn-based diets. Addition of supplemental Co to the basal diets increased (P < 0.01) plasma glucose concentrations of steers, and steers fed corn-based diets had greater plasma glucose than those fed barley-based diets. Steers supplemented with Co had greater ruminal propionate (P < 0.01) and lesser (P < 0.05) ruminal acetate and butyrate proportions than controls. Supplemental Co increased dressing percent (P < 0.10) and HCW (P < 0.01) at slaughter. These results indicate that feeding steers corn- or barley-based diets deficient in Co adversely affects performance and vitamin B12 status.}, number={11}, journal={Journal of Animal Science}, author={Tiffany, M. E. and Spears, J. W.}, year={2005}, pages={2580–2589} }
 @article{legleiter_spears_lloyd_2005, title={Influence of dietary manganese on performance, lipid metabolism, and carcass composition of growing and finishing steers}, volume={83}, DOI={10.2527/2005.83102434x}, abstractNote={A study was conducted to determine the effect of dietary Mn on performance of growing and finishing steers, and to evaluate the effect of pharmacological concentrations of Mn on lipid metabolism and subsequent carcass quality in steers. One hundred twenty Angus cross steers were blocked by BW and origin and assigned randomly to one of six treatments (four replicate pens per treatment) providing 0 (control), 10, 20, 30, 120, or 240 mg of supplemental Mn/kg of DM from MnSO4. Steers were fed a corn silage-based growing diet for 84 d, and then switched to a corn-based finishing diet for an average of 112 d. The control growing diet analyzed 29 mg of Mn/kg of DM, whereas the control finishing diet analyzed 8 mg of Mn/kg of DM. Jugular blood samples were obtained on d 56 of the growing and finishing phase for plasma Mn and glucose analysis. Final BW, DMI, ADG, and G:F did not differ (P = 0.38 to P = 0.98) across treatments during growing and finishing phases. Plasma Mn concentrations were not affected by treatment; however, liver and LM Mn at slaughter increased linearly (P = 0.02 and 0.002, respectively) with increasing dietary Mn. Plasma glucose concentrations did not differ (P = 0.90) among treatments. Serum nonesterified fatty acid concentrations tended (P = 0.10) to decrease linearly with increasing dietary Mn on d 56 of the finishing phase. Longissimus muscle lipid concentration was affected quadratically (P = 0.08) by dietary Mn. Muscle lipid seemed to increase slightly when steers were fed 30 or 120 mg of Mn/kg of DM, but decreased with the addition of 240 mg of Mn/kg of DM. Carcass characteristics were not affected by dietary Mn. Manganese concentrations of 29 and 8 mg/kg of DM in the growing and finishing diets, respectively, were adequate for maximizing performance of growing and finishing steers in this experiment. Supplementing physiological or pharmacological concentrations of Mn affected lipid metabolism; however, this did not result in altered carcass characteristics.}, number={10}, journal={Journal of Animal Science}, author={Legleiter, L. R. and Spears, J. W. and Lloyd, K. E.}, year={2005}, pages={2434–2439} }
 @article{arthington_spears_miller_2005, title={The effect of early weaning on feedlot performance and measures of stress in beef calves}, volume={83}, DOI={10.2527/2005.834933x}, abstractNote={Forty crossbred steers (Brahman x English) were categorized into two groups: 1) early weaned (EW; n = 20); and 2) normal weaned (NW; n = 20). Calves were 89 and 300 d of age at the time of EW and NW, respectively; SEM = 4.4. Early-weaned calves were kept on-site (University of Florida, Ona), provided supplement (1% of BW), and grazed on annual and perennial pastures until NW. At the time of normal weaning, all calves were loaded on a commercial livestock trailer and transported to the North Carolina State University Research Feedlot in Butner (approximately 1,200 km). Upon arrival, calves were stratified by BW and randomly allotted to four pens per weaning age treatment. Individual calf BW and blood samples were collected at the time of normal weaning, on arrival at the feedlot (d 1; 24 h following weaning), and on d 3, 7, 14, 21, and 28 of the receiving period. Individual BW was collected at the start and end of the growing and finishing periods, and feed intake by pen was measured daily. As an estimate of stress during the receiving period, plasma was collected and analyzed for the acute-phase proteins, haptoglobin and ceruloplasmin. Early-weaned calves were lighter (P = 0.03) at normal weaning than NW calves (221 vs. 269 kg; SEM = 10.6). By d 28, EW calves tended (P = 0.12) to be lighter than NW calves (242 vs. 282 kg, respectively). Gain:feed was improved for EW compared with NW calves during both the receiving (G:F = 0.157 vs. 0.081) and growing (0.159 vs. 0.136) periods. There tended (P < 0.10) to be weaning age x day interactions for each acute-phase protein. Ceruloplasmin concentrations increased in NW, but not EW calves, and peaked on d 7 (27.6 and 34.2 mg/100 mL for EW and NW calves, respectively; P < 0.05). Haptoglobin concentrations increased in both groups and were greatest (P < 0.05) in NW calves on d 3 (7.63 vs. 14.86 mg of haptoglobin/hemoglobin complexing/100 mL). No differences in ADG or G:F were detected during the finishing phase; however, overall G:F was improved (P = 0.03) for EW vs. NW calves (0.155 vs. 0.136). Carcass measures, including backfat thickness, USDA yield grade, marbling score, and LM area, did not differ between treatments. These data imply that EW calves, which are maintained onsite before shipping, may be more tolerant to the stressors associated with transportation and feed yard entry. Early weaned calves, managed within the system described in this study, may have improved G:F.}, number={4}, journal={Journal of Animal Science}, author={Arthington, J. D. and Spears, J. W. and Miller, D. C.}, year={2005}, pages={933–939} }
 @article{spears_kegley_mullis_2004, title={Bioavailability of copper from tribasic copper chloride and copper sulfate in growing cattle}, volume={116}, ISSN={["0377-8401"]}, DOI={10.1016/j.anifeedsci.2004.06.002}, abstractNote={Two experiments were conducted to determine the bioavailability of copper (Cu) from tribasic Cu chloride (Cu2(OH)3Cl) relative to Cu sulfate in growing steers. Experiment 1 compared tribasic Cu chloride to sulfate in terms of ability to maintain Cu status when supplemented to steers fed diets high in the Cu antagonists, molybdenum (Mo) and sulfur (S). Sixty Angus and Angus × Hereford steers (257 ± 2 kg body weight) were stratified by body weight and randomly assigned to treatments. Treatments consisted of 0, 5 or 10 mg supplemental Cu/kg diet DM from either Cu chloride or Cu sulfate. All diets were supplemented with 5 mg Mo/kg and 1.5 g S/kg. The control corn silage based diet analyzed 4.9 mg Cu/kg and 6.9 mg Mo/kg and was calculated to contain 3.0 g S/kg. Plasma and liver Cu concentrations and plasma ceruloplasmin activity decreased (P < 0.01) in all treatment groups during the 98-day study. Copper supplemented steers had higher (P < 0.01) plasma Cu, plasma ceruloplasmin, and liver Cu than controls at the end of the study. Steers supplemented with 10 mg Cu/kg had higher (P < 0.01) plasma Cu, plasma ceruloplasmin, and liver Cu than those receiving 5 mg Cu/kg diet. Bioavailability of Cu from Cu chloride, relative to Cu sulfate, was estimated from plasma Cu and ceruloplasmin on day 84 and liver Cu on day 98 using multiple linear regression and a slope ratio technique. Compared with Cu sulfate (1.00), relative bioavailability of Cu from tribasic Cu chloride was 1.32 (P < 0.08), 1.18 (P < 0.38) and 1.96 (P < 0.04) based on plasma Cu, plasma ceruloplasmin and liver Cu, respectively. In experiment 2, 43 Angus and Simmental steers (375 ± 7 kg BW) that had previously been depleted of Cu were used in a 21-day repletion study. Steers were randomly assigned within breed to treatment, and individually fed a corn silage based diet low in Mo (1.18 mg/kg). Treatments consisted of 0, 50 or 100 mg supplemental Cu/day from either Cu chloride or Cu sulfate. Plasma Cu, plasma ceruloplasmin and liver Cu increased (P < 0.01) in Cu supplemented, but not in control, steers. Plasma and liver Cu concentrations increased (P < 0.01) to a greater extent in steers receiving 100 mg Cu/day compared to those given 50 mg Cu/day. Tribasic Cu chloride and Cu sulfate were similar (P > 0.10) in their ability to increase Cu status in Cu depleted steers fed a diet low in Mo. Tribasic Cu chloride is more bioavailable than CuSO4 when added to diets high in the Cu antagonists Mo and S. When evaluated in Cu depleted steers fed diets low in Mo, the two Cu sources had a similar bioavailability.}, number={1-2}, journal={ANIMAL FEED SCIENCE AND TECHNOLOGY}, author={Spears, JW and Kegley, EB and Mullis, LA}, year={2004}, month={Sep}, pages={1–13} }
 @article{spears_schlegel_seal_lloyd_2004, title={Bioavailability of zinc from zinc sulfate and different organic zinc sources and their effects on ruminal volatile fatty acid proportions}, volume={90}, ISSN={["0301-6226"]}, DOI={10.1016/j.livprodsci.2004.05.001}, abstractNote={Twenty-four Angus steers were used to determine the effects of dietary zinc (Zn) level and source on Zn metabolism and ruminal volatile fatty acid (VFA) patterns. All steers were fed a low Zn diet (18.8 mg Zn per kg) for 42 days prior to assignment to dietary treatments. Treatments consisted of: (1) control (low Zn diet), (2) Zn sulfate (ZnSO4), (3) Zn methionine complex (ZnMet) and (4) Zn glycine complex (ZnGly). The Zn sources were added to provide 20 mg of supplemental Zn per kg diet. A 5-day total collection of feces and urine was conducted beginning on day 14 of the study. Liver biopsy samples were obtained on days 0 and 42 for Zn analysis, and ruminal fluid was collected on day 42 for VFA and ruminal soluble Zn determination. Plasma samples were obtained on days 0, 2, 19, 21, and 42 for determination of plasma Zn and alkaline phosphatase activity. Urinary excretion of Zn was higher (P<0.05) in steers supplemented with ZnMet or ZnGly than in controls. Apparent absorption and retention of Zn were not significantly affected by treatment, but tended to be higher in steers receiving ZnGly. Liver Zn concentrations were higher (P<0.05) on day 42 in steers supplemented with ZnGly, compared to steers receiving control, ZnMet or ZnSO4 treatments. Plasma Zn concentrations were higher (P<0.05) for the ZnGly and ZnMet treatments compared to the control on day 42. Plasma alkaline phosphatase was not affected by treatment. Ruminal soluble Zn concentrations were higher (P<0.05) in steers fed ZnMet compared to those fed the control or ZnSO4 diets. Total VFA concentrations were higher (P<0.05) in steers fed the control and ZnSO4 treatments than in those receiving ZnGly or ZnMet. Steers supplemented with ZnMet had a higher (P<0.05) molar proportion of propionate and lower (P<0.05) molar proportions of butyrate and valerate than controls. Compared to the control treatment, valerate was the only VFA affected by ZnSO4 or ZnGly supplementation. Results suggest that Zn from ZnGly was more bioavailable than ZnSO4 or ZnMet. However, ZnMet supplementation resulted in the highest ruminal soluble Zn concentrations and altered ruminal VFA proportions to the greatest extent of the Zn sources evaluated.}, number={2-3}, journal={LIVESTOCK PRODUCTION SCIENCE}, author={Spears, JW and Schlegel, P and Seal, MC and Lloyd, KE}, year={2004}, month={Nov}, pages={211–217} }
 @article{armstrong_cook_ward_williams_spears_2004, title={Effect of dietary copper source (cupric citrate and,cupric sulfate) and concentration on growth performance and fecal copper excretion in weanling pigs}, volume={82}, DOI={10.1093/ansci/82.4.1234}, number={4}, journal={Journal of Animal Science}, author={Armstrong, T. A. and Cook, D. R. and Ward, M. M. and Williams, C. M. and Spears, J. W.}, year={2004}, pages={1234–1240} }
 @article{creech_spears_flowers_hill_lloyd_armstrong_engle_2004, title={Effect of dietary trace mineral concentration and source (inorganic vs. chelated) on performance, mineral status, and fecal mineral excretion in pigs from weaning through finishing}, volume={82}, DOI={10.2527/2004.8272140x}, abstractNote={Two hundred and sixteen weanling gilts (6.65+/-0.08 kg) were used to determine the effects of decreasing supplemental concentrations of Zn, Cu, Fe, and Mn, and trace mineral source (inorganic vs. chelated) on growth performance, mineral status, and fecal mineral concentrations from weaning through development. The study was conducted over three trials with 72 pigs in each trial. Gilts were blocked by weight and randomly assigned to either 1) control, 2) reduced inorganic, or 3) reduced chelated trace minerals. The control diet was supplemented with 25, 150, 180, and 60 mg/kg of Cu, Zn, Fe, and Mn (in sulfate forms), respectively, during the nursery phase and 15, 100, 100, and 40 mg/kg of supplemental Cu, Zn, Fe, and Mn, respectively, during the growing and gilt-developer phases. Reduced inorganic and reduced chelated treatments were supplemented during all phases with 5, 25, 25, and 10 mg/kg of Cu, Zn, Fe, and Mn, respectively. The reduced chelated treatment supplied 50% of the supplemental Cu, Zn, Fe, and Mn in the form of metal proteinates, with the remainder from sulfate forms. Performance by control pigs did not differ from pigs fed the reduced trace mineral treatments during the nursery and grower-development periods. Gain:feed was lower (P < 0.05) for pigs fed the reduced inorganic compared with those fed the reduced chelated treatment during the nursery period. Trace mineral source did not affect performance during the growing or gilt-developer phase. Plasma Zn concentration and alkaline phosphatase activity were higher (P < 0.01) in control pigs than in those receiving reduced trace minerals during the nursery and growing phases. Plasma Cu concentration and ceruloplasmin activity were generally not affected by treatment. Hemoglobin concentrations were lower (P < 0.05) for the reduced inorganic compared with the reduced chelated treatment in the nursery phase. Fecal concentrations of Cu, Zn, and Mn were lower (P < 0.05) in pigs fed reduced trace minerals than in controls during all production phases. Fecal Zn concentration during the nursery and fecal Cu concentrations during the growing and gilt-developer phases were lower (P < 0.05) in pigs fed the reduced chelated compared with the reduced inorganic treatment. Results indicate that reducing the concentrations of Zn, Cu, Mn, and Fe typically supplemented to pig diets will greatly decrease fecal mineral excretion without negatively affecting pig performance from weaning through development.}, number={7}, journal={Journal of Animal Science}, author={Creech, B. L. and Spears, J. W. and Flowers, W. L. and Hill, G. M. and Lloyd, K. E. and Armstrong, T. A. and Engle, T. E.}, year={2004}, pages={2140–2147} }
 @article{engle_spears_2004, title={Effect of finishing system (feedlot or pasture), high-oil maize, and copper on conjugated linoleic acid and other fatty acids in muscle of finishing steers}, volume={78}, number={2}, journal={Animal Science (Penicuik, Scotland)}, author={Engle, T. E. and Spears, J.W.}, year={2004}, pages={261–269} }
 @article{wright_spears_2004, title={Effect of zinc source and dietary level on zinc metabolism in Holstein calves}, volume={87}, ISSN={["1525-3198"]}, DOI={10.3168/jds.S0022-0302(04)73254-3}, abstractNote={Forty-eight Holstein male calves were stratified by origin and body weight and randomly assigned to one of 4 treatment groups. Dietary treatments were administered in 2 phases. In phase 1, treatment groups received the basal diet with no supplemental Zn (control), basal diet plus 20 mg of Zn/kg of DM as ZnSO4 or Zn proteinate (ZnProt), or basal diet plus 20 mg of Zn/kg of DM with 50% of the Zn supplied from each source (ZnM) for 98 d. In phase 2, calves continued to receive the same Zn source fed in phase 1; however, half of the calves in each treatment group were randomly selected to receive 500 mg of Zn/kg of DM (HiZnSO4, HiZnProt, HiZnM) for 14 d. Gain, feed intake, and feed efficiency of calves were not affected by treatment in either phase of the experiment. Treatment had no affect on plasma Zn concentration or alkaline phosphatase activity in phase 1, but liver Zn concentration was greater in calves fed ZnSO4 than those fed ZnProt. In phase 2, plasma Zn was greater in calves fed HiZnProt and HiZnM than in those fed HiZnSO4. Liver Zn was greater in calves fed HiZnProt than in those fed HiZnSO4. Duodenal Zn concentrations were greater in calves supplemented with HiZnProt and HiZnM than those supplemented with HiZnSO4. Liver metallothionein was greater in calves that received 500 mg of Zn/kg than in calves that received 20 mg of Zn/ kg, but was not affected by Zn source. Calves fed HiZnProt and HiZnM had greater kidney Zn concentrations than those fed HiZnSO4. Heart, spleen, testicular, and bone Zn concentrations were not affected by Zn source. Hoof wall samples contained nearly 3-fold greater Zn concentrations than hoof sole. Calves fed ZnSO4 had greater Zn concentration in hoof wall samples than those fed ZnM. Hoof sole Zn concentration was not affected by Zn source or concentration. Plasma and tissue Zn concentrations at harvest were generally similar in calves supplemented with 20 mg of Zn/kg from ZnSO4 or ZnProt. However, when supplemented at 500 mg of Zn/kg, ZnProt was absorbed to a greater extent than ZnSO4, based on higher plasma, liver, duodenal, and kidney Zn concentrations.}, number={4}, journal={JOURNAL OF DAIRY SCIENCE}, author={Wright, CL and Spears, JW}, year={2004}, month={Apr}, pages={1085–1091} }
 @article{roberts_heugten_spears_routh_lloyd_almond_2004, title={Effects of dietary zinc on performance and immune response of growing pigs inoculated with porcine reproductive and respiratory syndrome virus and mycoplasma hyopneumoniae}, volume={17}, ISSN={["1976-5517"]}, DOI={10.5713/ajas.2004.1438}, abstractNote={The objective of this study was to determine the effects of dietary Zn level on performance, serum Zn concentrations, alkaline phosphatase activity (ALP), and immune response of pigs inoculated with Porcine Reproductive and Respiratory Syndrome virus (PRRSv) and Mycoplasma hyopneumoniae. A 2×4 factorial arrangement of treatments was used in a randomized design. Factors included; 1) PRRSv and M. hyopneumoniae inoculation (n=36 pigs) or sham inoculation (n=36 pigs) with media when pigs entered the grower facility (d 0) at 9 weeks of age and 2) 10, 50, 150 ppm supplemental Zn sulfate (ZnSO4) from weaning until the completion of the study, or 2,000 ppm supplemental ZnSO4 for two weeks in the nursery and then supplementation with 150 ppm ZnSO4 for the remainder of the trial. The basal diet contained 34 ppm Zn. Pigs were weighed on d 0, 10, 17, 24 and 31 and blood samples were collected on d 0, 7, 14, 21 and 28. Pigs inoculated with PRRSv were serologically positive at d 28 and control pigs remained negative to PRRSv. In contrast, the M hyopneumoniae inoculation was inconsistent with 33.3% and 52.8% of pigs serologically positive at d 28 in the control and infected groups, respectively. A febrile response was observed for approximately one week after inoculation with PRRSv. Feed intake (p<0.01) and gain (p<0.1) were less in PRRSv infected pigs than control pigs for the 31 d study. However, performance did not differ among pigs in the four levels of ZnSO4. Assessments of immune responses failed to provide unequivocal influence of either PRRSv inoculation or ZnSO4 level. These data suggest that PRRSv and M. hyopneumoniae act to produce some performance deficits and the influence of Zn supplementation of nursery age pigs does not have clear effect in grower pigs affected with disease. (Asian- Aust. J. Anim. Sci. 2004. Vol 17, No. 10 : 1438-1446)}, number={10}, journal={ASIAN-AUSTRALASIAN JOURNAL OF ANIMAL SCIENCES}, author={Roberts, ES and Heugten, E and Spears, JW and Routh, PA and Lloyd, KL and Almond, GW}, year={2004}, month={Oct}, pages={1438–1446} }
 @article{van heugten_o'quinn_funderburke_flowers_spears_2004, title={Growth performance, carcass characteristics, plasma minerals, and fecal mineral excretion in grower-finisher swine fed diets with levels of trace minerals lower than common industry levels}, volume={12}, number={5}, journal={Journal of Swine Health and Production}, author={Van Heugten, E. and O'Quinn, P. R. and Funderburke, D. W. and Flowers, W. L. and Spears, J. W.}, year={2004}, pages={237–241} }
 @article{spears_2003, title={Advances in mineral nutrition for ruminants studied}, volume={75}, ISBN={0014-9624}, number={29}, journal={Feedstuffs}, author={Spears, J. W.}, year={2003}, pages={12} }
 @article{armstrong_spears_2003, title={Effect of boron supplementation of pig diets on the production of tumor necrosis factor-alpha and interferon-gamma}, volume={81}, DOI={10.2527/2003.81102552x}, abstractNote={Two experiments were conducted to determine the effects of dietary B on the production of cytokines following an endotoxin challenge. In both experiments, pigs were obtained from litters generated from sows fed low-B (control) or B-supplemented (5 mg/ kg, as-fed basis) diets. In Exp. 1 and 2, 28 and 35 pigs, respectively (21 d old), remained with their littermates throughout a 49-d nursery phase and were fed either a control or B-supplemented diet. In Exp. 1, 12 pigs per treatment were moved to individual pens at the completion of the nursery phase and fed their respective experimental diet. On d 99 of the study, pigs were injected with 150 microg of phytohemagglutinin (PHA) to evaluate a local inflammatory response. Pigs receiving the B-supplemented diet had a decreased (P < 0.01) inflammatory response following PHA injection. Peripheral blood monocytes were isolated from six pigs per treatment on d 103 and cultured in the presence of lipopolysaccharide (LPS) to determine the effect of dietary B on tumor necrosis factor-alpha (TNF-alpha) production from monocytes. Isolated monocytes from pigs that received the B-supplemented diet had a numerically greater (P = 0.23) production of TNF-alpha. In Exp. 2, pigs were group housed with their littermates following the nursery phase for 43 d, after which 10 pigs per treatment were moved to individual pens. In Exp. 1 and 2, pigs were assigned randomly within dietary treatment to receive either an i.m. injection of saline or LPS on d 117 and d 109, respectively. The dose of LPS in Exp. 1 and 2 was 100 and 25 microg of LPS/kg of BW, respectively. In Exp. 1, serum TNF-alpha was increased (P < 0.01) at 2 h and tended to be increased (P < 0.11) at 6 and 24 h after injection by dietary B; however, only numerical trends existed for a B-induced increase in TNF-alpha in Exp. 2. Serum interferon-gamma (IFN-gamma) was increased (P < 0.01) at 6 h and tended to be increased (P < 0.08) at 24 h after injection in Exp. 1. In Exp. 2, dietary B also numerically increased IFN-alpha. These data indicate that dietary B supplementation increased the production of cytokines following a stress, which indicates a role of B in the immune system; however, these data do not explain the reduction in localized inflammation following an antigen challenge in pigs.}, number={10}, journal={Journal of Animal Science}, author={Armstrong, T. A. and Spears, J. W.}, year={2003}, pages={2552–2561} }
 @article{arthington_pate_spears_2003, title={Effect of copper source and level on performance and copper status of cattle consuming molasses-based supplements}, volume={81}, DOI={10.2527/2003.8161357x}, abstractNote={Two studies were conducted to evaluate the availability of dietary Cu offered to growing beef cattle consuming molasses-based supplements. In Exp. 1, 24 Braford heifers were assigned randomly to bahiagrass (Paspalum notatum) pastures (two heifers/pasture). Heifers were provided 1.5 kg of TDN and 0.3 kg of supplemental CP/heifer daily using a molasses-cottonseed meal slurry. Three treatments were randomly assigned to pastures (four pastures/treatment), providing 100 mg of supplemental Cu daily in the form of either CuSO4 (inorganic Cu) or organic-Cu. A third treatment offered no supplemental Cu (negative control). Heifer BW was collected at the start and end of the study. Jugular blood and liver samples were collected on d 0, 29, 56, and 84. In Exp. 2, 24 Brahman-crossbred steers were fed the same molasses-cottonseed meal supplement at the same rates used in Exp. 1. Steers were housed in individual pens (15 m2) with free-choice access to stargrass (Cynodon spp.) hay. Four Cu treatments were assigned to individual steers (six pens/treatment) providing 1) 10 ppm of Cu from an organic source; 2) 10 ppm Cu from Tri-basic Cu chloride (TBCC); 3) 30 ppm of Cu from TBCC; or 4) 30 ppm of Cu, a 50:50 ratio of TBCC and organic Cu. Body weights and jugular blood and liver samples were collected on d 0, 24, 48, and 72. In Exp. 1, liver Cu concentrations did not differ between heifers supplemented with inorganic and organic Cu. Each source resulted in increased (P < 0.05) liver Cu concentrations compared with the unsupplemented control. Plasma ceruloplasmin concentrations were higher (P < 0.05) for Cu-supplemented heifers, independent of Cu source. Heifer ADG tended (P = 0.11) to increase with Cu supplementation compared with the unsupplemented control. In Exp. 2, liver Cu was greater (P < 0.05) on d 24, 48, and 72 for steers consuming 30 vs. 10 ppm of Cu. Steers supplemented with organic Cu had lower DMI than steers supplemented with 10 or 30 ppm of TBCC. These data suggest that the inorganic and organic Cu sources evaluated in these studies were of similar availability when offered in molasses supplements. A dietary Cu concentration greater than 10 ppm might be necessary to ensure absorption in beef cattle fed molasses-based supplements.}, number={6}, journal={Journal of Animal Science}, author={Arthington, J. D. and Pate, F. M. and Spears, J. W.}, year={2003}, pages={1357–1362} }
 @article{mullis_spears_mccraw_2003, title={Effects of breed (Angus vs Simmental) and copper and zinc source on mineral status of steers fed high dietary iron}, volume={81}, DOI={10.2527/2003.811318x}, abstractNote={Forty-four Angus (n = 24) and Simmental (n = 20) steers, averaging 301 kg initially, were used to determine the effects of breed and Cu and Zn source (SO4 or proteinate (Prot) form) on Cu and Zn status of steers fed high dietary iron (Fe). Steers were stratified by weight within breed and randomly assigned to treatments. Treatments consisted of: 1) CuSO4 + ZnSO4 ,2) CuSO4 + ZnProt, 3) CuProt + ZnSO4, and 4) CuProt + ZnProt. Copper and Zn sources were added to provide 5 mg Cu and 25 mg supplemental Zn/kg DM. All steers were individually fed a corn silage-based diet supplemented with 1,000 mg Fe (from FeSO4)/kg DM. Liver biopsy samples were obtained at the beginning and end of the 149-d study. Serum samples were collected initially and at 28-d intervals for determination of ceruloplasmin activity and Zn and Cu concentrations. Copper and Zn source did not affect performance, serum or liver Cu and Zn concentrations, or ceruloplasmin activity. Copper status decreased (P < 0.01) in all steers with time, and increasing the level of supplemental Cu from 5 to 10 mg/kg DM on d 84 did not prevent further drops in serum Cu and ceruloplasmin. Simmental steers had lower (P < 0.05) serum and liver Cu concentrations, and serum ceruloplasmin activity throughout the study. These results indicate that neither CuSO4 nor CuProt were effective at the supplemental concentrations evaluated in alleviating the adverse effect of high Fe on Cu status. Simmental steers had lower Cu status than Angus, suggesting a higher Cu requirement.}, number={1}, journal={Journal of Animal Science}, author={Mullis, L. A. and Spears, J. W. and McCraw, R. L.}, year={2003}, pages={318–322} }
 @article{spears_engle_platter_lloyd_belk_horton_2003, title={Effects of high dietary calcium propionate and dietary cation-anion balance on calcium metabolism and longissimus muscle tenderness in finishing steers}, volume={19}, ISBN={1080-7446}, DOI={10.15232/s1080-7446(15)31461-3}, abstractNote={Abstract Forty-eight Angus and Angus-cross steers (initial BW = 657 ± 5.7 kg) were used in a 2 × 2 factorial design to determine whether feeding an anionic diet or high dietary concentrations of a soluble calcium (Ca propionate) source or both would alter Ca metabolism and subsequently longissimus tenderness. Treatments consisted of 1) control, 2) 4% Ca propionate (CaProp), 3) 2% NH 4 Cl (anionic diet), and 4) CaProp plus 2% NH 4 Cl. Experimental diets were fed for 7 d prior to slaughter. Steers were individually fed using electronic Calan gate feeders. Blood samples were obtained on d 3 and 7 at 2 h post feeding for plasma Ca determination. A striploin steak was obtained from each carcass at 48 h post harvest for muscle Ca analysis and Warner-Bratzler shear force (WBSF) determination. Addition of CaProp or NH 4 Cl to the high concentrate finishing diet reduced (P 4 Cl and CaProp, indicating that their effects were additive. Carcass characteristics were not affected by CaProp, but the anionic diet tended to reduce hot carcass weights (P=0.13) and longissimus areas (P=0.09). Plasma Ca concentrations were slightly greater in steers fed CaProp on d 3 (P}, number={6}, journal={Professional Animal Scientists}, author={Spears, J. W. and Engle, T. E. and Platter, W. R. and Lloyd, K. E. and Belk, K. E. and Horton, J.}, year={2003}, pages={424} }
 @article{heugten_spears_kegley_ward_qureshi_2003, title={Effects of organic forms of zinc on growth performance, tissue zinc distribution, and immune response of weanling pigs}, volume={81}, DOI={10.2527/2003.8182063x}, abstractNote={This study was conducted to determine the effect of zinc level and source on growth performance, tissue Zn concentrations, intracellular distribution of Zn, and immune response in weanling pigs. Ninety-six 3-wk-old crossbred weanling pigs (BW = 6.45 +/- 0.17 kg) were assigned to one of six dietary treatments (four pigs per pen, four replicates per treatment) based on weight and litter origin. Treatments consisted of the following: 1) a corn-soybean meal-whey diet (1.2% lysine) with a basal level of 80 ppm of supplemental Zn from ZnSO4 (control; contained 104 ppm total Zn); 2) control + 80 ppm added Zn from ZnSO4; 3) control + 80 ppm added Zn from Zn methionine (ZnMet); 4) control + 80 ppm added Zn from Zn lysine (ZnLys); 5) control + 40 ppm added Zn from ZnMet and 40 ppm added Zn from ZnLys (ZnML); and 6) control + 160 ppm added Zn from ZnSO4. Zinc supplementation of the control diet had no effect on ADG or ADFI. Gain efficiency was less (P < 0.05) for pigs fed 80 ppm of Zn from ZnSO4 than for control pigs and pigs fed 160 ppm of Zn from ZnSO4. Organ weights, Zn concentration, and intracellular distribution of Zn in the liver, pancreas, and spleen were not affected (P = 0.12) by Zn level or source. Skin thickness response to phytohemagglutinin (PHA) was not affected (P = 0.53) by dietary treatment. Lymphocyte proliferation in response to PHA was greater (P < 0.05) in pigs fed ZnLys than in pigs fed the control diet or the ZnML diet; however, when pokeweed mitogen was used, lymphocyte proliferation was greatest (P < 0.05) in pigs fed the ZnMet diet than pigs fed the control, ZnLys, ZnML, or 160 ppm ZnSO4 diets. Antibody response to sheep red blood cells was not affected by dietary treatments. Supplementation of 80 ppm of Zn from ZnSO4 or ZnMet and 160 ppm of Zn from ZnSO4 decreased (P < 0.05) the antibody response to ovalbumin on d 7 compared with control pigs, but not on d 14. Phagocytic capability of peritoneal exudate cells was increased (P < 0.05) when 160 ppm of Zn from ZnSO4 was supplemented to the diet. The number of red blood cells ingested per phagocytic cell was increased (P < 0.05) in pigs fed the diet supplemented with a combination of ZnMet and ZnLys and the diet with 160 ppm of Zn from ZnSO4. Results suggest that the level of Zn recommended by NRC for weanling pigs was sufficient for optimal growth performance and immune responses, although macrophage function may be enhanced at greater levels of Zn. Source of Zn did not alter these measurements.}, number={8}, journal={Journal of Animal Science}, author={Heugten, Eric and Spears, J. W. and Kegley, E. B. and Ward, J. D. and Qureshi, M. A.}, year={2003}, pages={2063–2071} }
 @article{mullis_spears_mccraw_2003, title={Estimated copper requirements of Angus and Simmental heifers}, volume={81}, DOI={10.2527/2003.814865x}, abstractNote={In Exp. 1, Simmental (n = 21) and Angus (n = 21) heifers, approximately 9 mo of age, were used in a 160-d study to determine the effect of dietary Cu on growth and Cu status. Two- or three-yr-old first-calf heifers (21 Angus and 21 Simmental) entering into their last trimester of pregnancy were used in Exp. 2 to estimate Cu requirements of the two breeds during gestation and early lactation. Treatments in both studies consisted of 0 (control), 7, or 14 mg of supplemental Cu (as CuSO4)/kg of DM. The control corn silage-based diets contained 6.4 and 4.4 mg of Cu/kg of DM in Exp. 1 and 2, respectively, and 1.2 mg of Mo/kg. Dietary Cu did not affect performance in either breed in Exp. 1. Copper supplementation generally did not affect plasma Cu concentrations in Angus heifers, but increased (P < 0.05) plasma Cu in Simmental heifers from d 37 until the end of Exp. 1. Final liver Cu concentrations were lower (P < 0.05) than initial concentrations in control Angus and Simmental heifers; however, liver Cu increased (P < 0.01) in Cu-supplemented heifers. In Exp. 2, Cu supplementation of the control diet increased (P < 0.05) plasma Cu during gestation and greatly increased (P < 0.01) liver Cu in both breeds. Calves born to cows not supplemented with Cu also had lower plasma Cu concentrations than Cu-supplemented calves by 73 d of age. In both studies, control Simmental heifers had lower (P < 0.05) plasma Cu concentrations than Angus on most sampling dates. When Cu was supplemented at 7 or 14 mg/kg of DM,few differences in plasma Cu concentrations were observed between breeds. Results suggest that Angus heifers have a lower minimal Cu requirement than Simmental. Based on liver Cu, the control diets containing 4.4 or 6.4 mg of Cu/kg of DM did not meet the Cu requirement of either breed during gestation and lactation or growth. Addition of 7 mg of Cu/kg of DM to the control diets met Cu requirements of both breeds.}, number={4}, journal={Journal of Animal Science}, author={Mullis, L. A. and Spears, J. W. and McCraw, R. L.}, year={2003}, pages={865–873} }
 @article{tiffany_spears_xi_horton_2003, title={Influence of dietary cobalt source and concentration on performance, vitamin B12 status, and ruminal and plasma metabolites in growing and finishing steers}, volume={81}, ISSN={0021-8812 1525-3163}, url={http://dx.doi.org/10.2527/2003.81123151x}, DOI={10.2527/2003.81123151x}, abstractNote={Sixty Angus steers, averaging 274 kg, were used to evaluate the effects of Co source and concentration on performance, vitamin B12 status, and metabolic characteristics of steers. Treatments consisted of 0 (control, analyzed 0.04 mg Co/kg), 0.05, 0.10, and 1.0 mg of supplemental Co/kg of DM from CoCO3 or 0.05 and 0.10 mg of supplemental Co/kg of DM from Co propionate. Steers were individually fed a growing diet for 56 d followed by a high-concentrate finishing diet. Performance was not affected by Co supplementation during the growing phase. During the finishing phase, ADFI (DM basis) and ADG were higher (P < 0.05) for the entire finishing phase, and gain:feed was higher (P < 0.10) over the first 56 d for Co-supplemented steers. Steers supplemented with 0.10 mg Co/kg as Co propionate had higher (P < 0.05) ruminal propionate and lower (P < 0.05) acetate molar proportions than steers receiving 0.10 Co/kg as CoCO3 during the growing phase. Supplemental Co increased (P < 0.10) molar proportion of propionate during the finishing phase. Plasma vitamin B12 was higher (P < 0.05) in Co-supplemented steers by d 56 of the growing phase and remained higher (P < 0.10) throughout the study. Control steers had higher (P < 0.05) plasma methylmalonic acid on d 56 of the growing phase and on d 28, 56, and 112 of the finishing phase than steers receiving supplemental Co. Steers supplemented with Co had higher plasma glucose at d 56 (P < 0.01), 84 (P < 0.10), and 112 (P < 0.01) of the finishing phase. Steers supplemented with 0.10 mg Co/kg as Co propionate had higher plasma glucose than those receiving 0.10 mg Co/kg as CoCO3 at d 28 of the growing phase (P < 0.05) and d 28 of the finishing phase (P < 0.10). Final body weight and hot carcass weight were lower (P < 0.10) in steers receiving the control diet, whereas other carcass characteristics were not affected by dietary Co. Average daily gain and feed efficiency for the entire finishing phase did not differ among Co-supplemented steers. However, increasing supplemental Co above 0.05 mg/kg DM (total diet Co = 0.09 mg/kg) resulted in increased (P < 0.01) plasma (linear) and liver (quadratic) vitamin B12 concentrations and decreased (quadratic, P < 0.10) plasma methylmalonic acid concentrations toward the end of the finishing phase. These results suggest that finishing steers require approximately 0.15 mg Co/kg of DM. Vitamin B12 status was not affected by Co source; however, the two Co sources seemed to affect certain metabolites differently.}, number={12}, journal={Journal of Animal Science}, publisher={Oxford University Press (OUP)}, author={Tiffany, M. E. and Spears, J. W. and Xi, L. and Horton, J.}, year={2003}, month={Dec}, pages={3151–3159} }
 @article{spears_2003, title={Trace mineral bioavailability in ruminants}, volume={133}, DOI={10.1093/jn/133.5.1506s}, abstractNote={Absorption of selenium and copper is much lower in ruminants than in nonruminants. The low absorption of these minerals in ruminants is due to modifications that occur in the rumen environment. Selenium bioavailability is reduced by high dietary sulfur and the presence of cyanogenetic glycosides in certain legumes. Feeding organic selenium from selenomethionine or selenized yeast results in much higher tissue and milk selenium concentrations than are obtained with selenite. High dietary molybdenum in combination with moderate to high dietary sulfur results in formation of thiomolybdates in the rumen. Thiomolybdates greatly reduce copper absorption, and certain thiomolybdate species can be absorbed and interfere systemically with copper metabolism. Independent of molybdenum, high dietary sulfur reduces copper absorption perhaps via formation of copper sulfide. High dietary iron also reduces copper bioavailability. Dietary factors that affect bioavailability of zinc in ruminants are not well defined. Phytate does not affect zinc absorption in ruminants because microbial phytase in the rumen degrades phytate. Manganese is very poorly absorbed in ruminants, and limited research suggests that high dietary calcium and phosphorus may reduce manganese absorption.}, number={5}, journal={Journal of Nutrition}, author={Spears, J. W.}, year={2003}, pages={1506S–1509} }
 @article{roberts_heugten_lloyd_almond_spears_2002, title={Dietary zinc effects on growth performance and immune response of endotoxemic growing pigs}, volume={15}, ISSN={["1976-5517"]}, DOI={10.5713/ajas.2002.1496}, abstractNote={A 2×3 factorial arrangement of treatments was used in a completely randomized design to determine the effects of dietary Zn on performance and immune response of acutely endotoxemic growing pigs (n=96, mean BW=24.9 kg). Factors included 1) intramuscular injection of 10 µg/kg BW of Escherichia coli lipopolysaccharide (LPS) or control and 2) supplemental Zn at 10, 50, or 150 ppm. Diets were fed beginning after weaning (initial body weight=7.6 kg) in the nursery and continued for 16 d into the grower phase. The basal corn-soybean meal grower diet contained 1% lysine and 34.3 ppm Zn. Pigs were acclimated for 12 d in the grower- finishing facility before LPS treatment on d 13. Gain, feed intake, and feed efficiency were unaffected by dietary Zn. Feed intake decreased (p<0.10) and gain/feed was greater (p<0.10) from d 13 to d 16 for pigs injected with LPS. Serum Zn and alkaline phosphatase activity increased (p<0.05) with increasing Zn levels. The febrile response to LPS peaked at 6 h post exposure and pigs were afebrile within 12 h. Rectal temperature was greater (p<0.05) in pigs receiving 50 and 150 ppm Zn than in pigs supplemented with 10 ppm Zn. In vivo cellular immune response, measured on d 13 by skin thickness response to phytohemagglutinin (PHA), was greater after 6 h (p< 0.05) in pigs fed 10 ppm Zn and exposed to LPS compared to all other treatments, but was not affected at 12, 24 or 48 h. Zinc did not affect mitogen induced lymphocyte proliferation. Zinc supplemented at 50 or 150 ppm resulted in an enhanced febrile response in pigs subjected to iatrogenic endotoxemia, but did not affect pig performance or immune response measurements. (Asian-Aust. J. Anim. Sci. 2002. Vol 15, No. 10 : 1496-1501)}, number={10}, journal={ASIAN-AUSTRALASIAN JOURNAL OF ANIMAL SCIENCES}, author={Roberts, ES and Heugten, E and Lloyd, K and Almond, GW and Spears, JW}, year={2002}, month={Oct}, pages={1496–1501} }
 @article{spears_kegley_2002, title={Effect of zinc source (zinc oxide vs zinc proteinate) and level on performance, carcass characteristics, and immune response of growing and finishing steers}, volume={80}, DOI={10.1093/ansci/80.10.2747}, abstractNote={Sixty Angus and Angus × Hereford steers (246 kg initial BW) were used to determine the effects of Zn level and source on performance, immune response, and carcass characteristics of growing and finishing steers. Treatments consisted of 1) control (no supplemental Zn), 2) ZnO, 3) Zn proteinate-A (ZnProt-A, 10% Zn), and 4) ZnProt-B (15% Zn). Treatments 2, 3, and 4 supplied 25 mg of supplemental Zn/kg diet. Steers were individually fed a corn silage-based diet during the 84-d growing phase and a high corn diet during the finishing phase. Cell-mediated and humoral immune response measurements were obtained between d 67 and 74 of the growing phase. Equal number of steers per treatment were slaughtered after receiving the finishing diets for 84 or 112 d. Performance and carcass measurements were similar in steers fed the two ZnProt sources. Zinc supplementation, regardless of source, increased (P < 0.05) ADG during the growing phase. In the finishing phase, ADG (P = 0.10) and gain/feed (P = 0.07) tended to be higher for steers fed ZnProt compared with those supplemented with ZnO. Gain and feed efficiency were similar for control and ZnO-supplemented steers during the finishing phase. Steers fed ZnProt had heavier (P < 0.05) hot carcass weights and slightly higher (P < 0.05) dressing percentages than those in the control or ZnO treatments. Quality grade, yield grade, marbling, and backfat were increased by Zn supplementation, but were not affected by Zn source. In vitro response of lymphocytes to mitogen stimulation and in vivo swelling response following intradermal injection of phytohemagglutinin were not affected by Zn level or source. Humoral immune response following vaccination with infectious bovine rhinotracheitis also was not affected by treatment. Soluble concentrations of Zn in ruminal fluid were higher (P < 0.05) in steers fed ZnProt compared to ZnO steers. Results indicate that ZnProt may improve performance of finishing steers above that observed with inorganic Zn supplementation.}, number={10}, journal={Journal of Animal Science}, author={Spears, J. W. and Kegley, E. B.}, year={2002}, pages={2747–2752} }
 @article{kegley_spears_flowers_schoenherr_2002, title={Iron methionine as a source of iron for the neonatal pig}, volume={22}, ISSN={["0271-5317"]}, DOI={10.1016/s0271-5317(02)00434-7}, abstractNote={Neonatal pigs (143) were used to determine if adequate iron (Fe) would be stored following a single oral dose of Fe methionine (FeMet) to prevent anemia through 21 d of age. Treatments consisted of: control (no Fe), 200 mg injectable Fe as gleptoferron within 12 h of birth (at birth), 100 or 200 mg Fe as FeMet orally at birth, or 200 mg Fe as FeMet or FeSO4 orally on d 3. Pigs given injectable Fe had higher hemoglobin concentrations than other treatments at 14 and 21 d. Utilization of Fe from FeMet was greatest when given at 3 d compared to at birth. Based on hemoglobin concentrations at 21 d, relative bioavailability of Fe from FeMet given on d 3 was 180% compared to FeSO4. Iron methionine given orally was a safe, effective source of Fe, but a single oral dose of FeMet was not equivalent to injectable Fe.}, number={10}, journal={NUTRITION RESEARCH}, author={Kegley, EB and Spears, JW and Flowers, WL and Schoenherr, WD}, year={2002}, month={Oct}, pages={1209–1217} }
 @article{armstrong_flowers_spears_nielsen_2002, title={Long-term effects of boron supplementation on reproductive characteristics and bone mechanical properties in gilts}, volume={80}, DOI={10.2527/2002.801154x}, abstractNote={An experiment was conducted to determine long-term effects of dietary boron (B) on reproductive and bone characteristics in gilts. Weanling gilts (n = 50) were allotted to 10 pens based on weaning weight and litter origin. Pens were randomly assigned to receive one of two dietary treatments that consisted of a basal diet low in B (control) and the basal diet supplemented with 5 mg of B/kg diet as sodium borate. Gilts remained on their respective experimental diets throughout the nursery phase, growing-finishing phase, sexual maturity, breeding, gestation, and lactation. The day of first observed standing estrus was defined as puberty, and each pubertal gilt was bred via AI at the second observed standing estrus. Eight randomly selected gilts per treatment were slaughtered at d 35 of gestation for the assessment of embryonic and reproductive characteristics, bone characteristics, and tissue B concentrations. The remaining pregnant gilts (control, n = 11; 5 mg supplemental B/kg diet, n = 10) farrowed, and litter characteristics at farrowing and weaning were determined. Age at puberty was not affected (P = 0.72) by B, and neither were the number of corpora lutea on the ovaries (P = 0.44) or the total number of embryos (P = 0.95) at d 35 of gestation. Boron supplementation increased (P = 0.05) pig weaning weight and tended (P = 0.11) to increase pig birth weight; however, no other litter characteristics were affected (P > 0.12) by B. Extrinsic and intrinsic strength measures of bone were increased (P < 0.09) by B. Fat-free bone ash percentage and bone mineral concentrations were not affected (P > or = 0.19) by dietary B. Supplemental B increased (P < or = 0.06) the B concentrations of the muscle, liver, and reproductive tissues. Serum osteocalcin concentrations tended (P = 0.13) to be increased by dietary B, which may be related to increased bone turnover in B-supplemented gilts. Results indicate that B may have beneficial effects upon reproductive and bone characteristics.}, number={1}, journal={Journal of Animal Science}, author={Armstrong, T. A. and Flowers, W. L. and Spears, J. W. and Nielsen, F. H.}, year={2002}, pages={154–161} }
 @article{engle_fellner_spears_2001, title={Copper status, serum cholesterol, and milk fatty acid profile in Holstein cows fed varying concentrations of copper}, volume={84}, ISSN={["1525-3198"]}, DOI={10.3168/jds.S0022-0302(01)74678-4}, abstractNote={An experiment was conducted to determine the effects of dietary copper (Cu) on Cu status and lipid metabolism in Holstein cows. Three primiparous and 21 multiparous Holstein cows were utilized in this experiment. Groups of three cows similar in parity, days in milk, and milk yield were assigned randomly to one of the following three treatments: 1) control (no supplemental Cu), 2) 10 mg of Cu/kg of DM from Cu sulfate (CuSO4), and 3) 40 mg of Cu/kg of DM from CuSO4. Liver Cu concentrations were higher in Cu supplemented cows at the end of the 61-d study. Cows receiving 40 mg of Cu/kg of DM had higher liver Cu concentrations than cows receiving 10 mg of Cu. Plasma Cu concentrations were similar across treatments. Total serum cholesterol concentrations were higher in cows receiving supplemental Cu. Cows receiving 40 mg of Cu/kg of DM had higher serum cholesterol concentrations than cows receiving 10 mg of Cu. Dry matter intake, average daily milk production, and milk lipid, protein, and somatic cell numbers were similar across treatments. On d 61, milk fatty acids C18:1 trans and C18-conjugated dienes were lower in cows receiving supplemental Cu relative to the nonsupplemented controls. Cows receiving 40 mg of Cu/kg of DM had higher C12:0 and lower C18:2 and total polyunsaturated fatty acids in milk than cows receiving 10 mg of Cu/kg of DM. These results indicate that Cu supplementation alters lipid metabolism in high producing dairy cows and that Cu supplementation at 40 mg/kg of DM for 61 d can elevate liver Cu concentrations to levels considered to be marginally toxic in dairy cattle.}, number={10}, journal={JOURNAL OF DAIRY SCIENCE}, author={Engle, TE and Fellner, V and Spears, JW}, year={2001}, month={Oct}, pages={2308–2313} }
 @article{kegley_spears_auman_2001, title={Dietary phosphorus and an inflammatory challenge affect performance and immune function of weanling pigs}, volume={79}, DOI={10.2527/2001.792413x}, abstractNote={Ninety-six 3-wk-old pigs (6.3+/-0.12 kg initial BW) were allotted to one of eight treatments based on BW and litter origin to determine the effect of dietary phosphorus and an inflammatory challenge on performance and immune function. Four corn-soybean meal-based treatment diets were formulated to contain 0.16, 0.24, 0.32, or 0.40% available P. Monocalcium-dicalcium phosphate was used as the supplemental P source. The Ca:available P ratio was maintained at 2:1. To challenge the pigs, half of the pigs in each dietary treatment were injected i.m. with E. coli lipopolysaccharide (200 microg/kg of BW) on d 7 and 14. This resulted in a 2 x 4 factorial arrangement of treatments. Average daily gain for the 35-d study was increased linearly (P < 0.01) by increasing supplemental P. Average daily gain and ADFI were decreased (P < 0.05) by lipopolysaccharide injection. Serum P concentrations increased linearly (P < 0.01) with increasing supplemental P. Antibody titers to the injection of sheep red blood cells and ovalbumin on d 21 decreased linearly (P < 0.10) by increasing supplemental P. In vitro blastogenic response of lymphocytes to phytohemagglutinin (PHA) on d 25 was increased linearly (P < 0.05) by increasing supplemental P. Blastogenic response of lymphocytes to pokeweed mitogen on d 25 was not affected. On d 31, skinfold thickness 6 h following an intradermal injection of PHA was increased quadratically (P < 0.07) by increasing supplemental P. There were no P x lipopolysaccharide interactions for any immune response measure. In conclusion, increasing supplemental P increased ADG and enhanced cell-mediated immune response but decreased humoral immune response.}, number={2}, journal={Journal of Animal Science}, author={Kegley, E. B. and Spears, J. W. and Auman, S. K.}, year={2001}, pages={413–419} }
 @article{armstrong_spears_2001, title={Effect of dietary boron on growth performance, calcium and phosphorus metabolism, and bone mechanical properties in growing barrows}, volume={79}, DOI={10.2527/2001.79123120x}, abstractNote={An experiment was conducted to evaluate the effects of dietary boron (B) on growth performance, bone mechanical properties, and calcium (Ca) and phosphorus (P) metabolism in pigs. Thirty-six barrows were weaned at approximately 21 d of age and randomly assigned to receive one of three dietary treatments. Treatments consisted of 1) low-B basal diet (control), 2) basal + 5 mg B/kg diet, and 3) basal + 15 mg B/kg diet. Boron was supplemented as sodium borate. Barrows remained on their respective experimental diets throughout the nursery (35 d) and growing (30 d) phases of production. Blood samples were obtained from each barrow at the end of each phase. Following the 30-d growing period, eight barrows per treatment were transferred to stainless steel metabolism crates. Barrows had an adjustment period of 7 d, followed by a 7-d total collection of urine and feces. All barrows were fed at 90% of the previous ad libitum grower intake of the control animals during the adjustment and collection periods. At the end of the 7-d collection period, barrows were killed and femurs and fibulas were harvested for the assessment of bone mechanical properties. During the nursery phase, ADG and ADFI were increased (P < 0.05) by B supplementation. Boron did not affect (P = 0.34) feed efficiency during the nursery phase. During the growing phase, ADG and ADFI were increased (P < 0.05) by B supplementation. Boron did not affect (P = 0.97) feed efficiency during the growing phase. Boron did not affect (P = 0.44) bone ash percentage, but B supplementation increased (P < 0.05) bone ash P. Ultimate shear force of the fibula was increased (P < 0.05) in barrows supplemented with 15 mg B/kg diet compared to barrows fed diets supplemented with 5 mg B/kg diet. Apparent absorption and retention of Ca and P were not affected (P > 0.05) by dietary B. These data indicate that B supplementation to pigs can increase growth and bone strength without greatly affecting Ca and P metabolism.}, number={12}, journal={Journal of Animal Science}, author={Armstrong, T. A. and Spears, J. W.}, year={2001}, pages={3120–3127} }
 @article{armstrong_spears_engle_see_2001, title={Effect of pharmacological concentrations of dietary copper on lipid and cholesterol metabolism in pigs}, volume={21}, ISSN={["0271-5317"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0034754358&partnerID=MN8TOARS}, DOI={10.1016/s0271-5317(01)00332-3}, abstractNote={An experiment was conducted to determine if pharmacological concentrations of copper (Cu) affect lipid and cholesterol metabolism in Cu-adequate pigs. Treatments consisted of: control (10 ppm Cu as cupric sulfate, CuSO4); control + 66 or 225 ppm Cu as CuSO4; control + 33, 66, or 100 ppm Cu as cupric citrate (CuCit). Pigs were fed their respective diets throughout the nursery (35 d) and growing-finishing (GF; 103 d) phases. Copper increased (P < .05) serum cholesterol during the nursery phase, but 100 ppm CuCit decreased (P < .05) serum cholesterol relative to the control on d 42 of the GF phase. Serum triglycerides were increased (P < .05) by 225 ppm CuSO4 relative to the control on d 42 of the GF phase. Percent lipid and cholesterol concentrations of the semitendinosus muscle were not affected by Cu. Lipid percentage of the longissimus muscle was decreased (P < .06) by 225 ppm CuSO4 compared to the control, but Cu did not affect cholesterol concentration or fatty acid profile. These results indicate that pharmacological concentrations of Cu have little effect on cholesterol and lipid metabolism in the Cu-adequate pig.}, number={9}, journal={NUTRITION RESEARCH}, author={Armstrong, TA and Spears, JW and Engle, TE and See, MT}, year={2001}, month={Sep}, pages={1299–1308} }
 @article{huntington_poore_hopkins_spears_2001, title={Effect of ruminal protein degradability on growth and N metabolism in growing beef steers}, volume={79}, DOI={10.2527/2001.792533x}, abstractNote={The objective of two experiments was to correlate plasma levels of urea N (PUN) and the percentage of urine N in the form of urea (UUN) to weight gain in response to different dietary protein regimens for growing Angus steers. In Exp. 1, 60 steers (302 kg BW) were assigned to various levels of dietary N (control plus supplemental N to provide from 100 to 400 g more crude protein daily) within two sources of supplemental N (soybean meal [SBM] or a mixture of two parts corn gluten meal:one part blood meal [CGM:BM]). In Exp. 2, 27 steers (229 kg BW) were fed two levels of SBM, and half of the steers received growth-promoting implants. Steers were housed in groups of 12 and fed individually for 84 d in both experiments. Corn silage was fed at a restricted rate to minimize orts. Jugular blood and urine samples were collected during the experiments. In Exp. 1, maximal ADG of steers fed SBM (1.0 kg) was reached with 671 g/d total crude protein, or 531 g/d metabolizable protein. Maximal ADG of steers fed CGM:BM (0.91 kg) was reached with 589 g/d total crude protein, or 539 g/d metabolizable protein. The DMI was higher (P < 0.07) for steers fed SBM (6.37 kg/d) than for steers fed CGM:BM (6.14 kg/d). Increasing ruminal escape protein from 36% (SBM) to 65% (CGM:BM) of CP decreased (P < 0.05) endogenous production of urea, as evidenced by lower concentrations of urea in blood and lower UUN. In Exp. 2, increasing supplemental protein from 100 to 200 g/d increased (P < 0.05) ADG and PUN. Implants lowered (P < 0.05) UUN, particularly at the higher level of supplemental protein. Protein supplementation of growing steers can be managed to maintain acceptable ADG yet decrease excretion of urea in the urine.}, number={2}, journal={Journal of Animal Science}, author={Huntington, G. and Poore, M. and Hopkins, B. and Spears, J.}, year={2001}, pages={533–541} }
 @article{armstrong_spears_lloyd_2001, title={Inflammatory response, growth, and thyroid hormone concentrations are affected by long-term boron supplementationin gilts}, volume={79}, DOI={10.2527/2001.7961549x}, abstractNote={An experiment was conducted to determine the long-term effects of dietary boron (B) on growth performance, immune function, and plasma and serum characteristics in gilts. Fifty weanling gilts were allotted to 10 pens based on weaning weight and litter origin. Pens were randomly assigned to receive one of two dietary treatments. Treatments consisted of a basal diet low in B (control) and the basal diet supplemented with 5 mg B/kg diet as sodium borate. Gilts remained on their respective experimental diets and with their penmates throughout the nursery, growing, and finishing phases. The B concentration of the basal diet was 0.98, 2.1, and 2.2 mg/kg diet during the nursery, growing, and finishing phases, respectively. At the end of each production phase, animals were weighed and feed consumption was determined to assess growth performance variables. In addition, blood samples were obtained from three randomly selected gilts per pen at the completion of each phase. Boron had no affect (P > 0.58) on growth performance during the nursery phase, but gilts receiving supplemental B had increased (P < 0.05) ADG at the end of the finishing phase and over the entire growing-finishing period. Serum concentrations of triiodothyronine (T3) tended (P < 0.07) to be reduced by dietary B at the end of the nursery phase, but serum thyroxine (T4) was not affected (P = 0.46) by B. At the completion of the growing phase, supplemental B decreased (P < 0.05) the concentrations of T3 and T4 in the serum. In addition, serum concentrations of total cholesterol and the activity of alkaline phosphatase were increased (P < 0.05) by dietary B at the end of the growing phase. Serum concentrations of urea N tended (P < 0.09) to be increased by B at the end of the growing phase. Beginning at d 95 of the experimental period, measures of immune function were assessed in randomly selected gilts. Boron decreased (P < 0.05) the inflammatory response to an intradermal injection of phytohemagglutinin. Boron did not affect (P > 0.30) the blastogenic response of isolated lymphocytes to mitogen stimulation or the humoral immune response against a sheep red blood cell suspension. Results indicate that B may affect serum thyroid hormone concentrations, the inflammatory response, and growth in pigs.}, number={6}, journal={Journal of Animal Science}, author={Armstrong, T. A. and Spears, J. W. and Lloyd, K. E.}, year={2001}, pages={1549–1556} }
 @article{engle_spears_2001, title={Performance, carcass characteristics, and lipid metabolism in growing and finishing Simmental steers fed varying concentrations of copper}, volume={79}, DOI={10.2527/2001.79112920x}, abstractNote={An experiment was conducted to determine the effects of dietary copper (Cu) on performance, carcass characteristics, and lipid metabolism in Simmental steers. Thirty-six Simmental steers (329.3 +/-11.4 kg) were stratified by weight and randomly assigned to treatments. Treatments consisted of the following: control (no supplemental Cu) and 10 or 40 mg Cu/kg DM from Cu sulfate. Each treatment consisted of six replicate pens, with each pen containing two steers. A corn silage-soybean meal-based diet was fed for 56 d. Steers were then switched to a high concentrate diet. Performance was not affected by treatment during the growing or finishing phases. Plasma Cu concentrations were higher (P < 0.05) in steers receiving supplemental Cu by d 56 of the growing phase and remained higher (P < 0.05) at all 28-d sampling periods during the finishing phase. Liver Cu concentrations were higher (P < 0.001) in steers receiving supplemental Cu at the end of the growing phase and on d 84 and at the end of the finishing phase. Steers supplemented with 40 mg Cu had higher (P < 0.001) liver Cu concentrations than those supplemented with 10 mg Cu/kg DM. Serum and longissimus muscle cholesterol concentrations were similar between treatments. Longissimus muscle and backfat fatty acid composition was similar between treatments. These results indicate that Cu supplementation given to Simmental steers increased Cu status but had no effect on performance, carcass characteristics, or lipid or cholesterol metabolism.}, number={11}, journal={Journal of Animal Science}, author={Engle, T. E. and Spears, J. W.}, year={2001}, pages={2920–2925} }
 @article{armstrong_spears_crenshaw_nielsen_2000, title={Boron supplementation of a semipurified diet for weanling pigs improves feed efficiency and bone strength characteristics and alters plasma lipid metabolites}, volume={130}, ISSN={["1541-6100"]}, DOI={10.1093/jn/130.10.2575}, abstractNote={Two experiments were conducted to determine effects of dietary boron (B) on performance, plasma minerals and metabolites, and bone characteristics in young pigs. In Experiment 1, 48 pigs (24 males, 24 females; 21 d old) were allotted to pens, which were randomly assigned to one of the following dietary treatments: 1) control (natural ingredient diet; 6.7 mg B/kg diet), 2) control + 5 mg B/kg diet and 3) control + 15 mg B/kg diet. Boron was supplemented as sodium borate. In Experiment 2, 48 pigs (24 males, 24 females; 21 d old) were assigned to the same treatments described in Experiment 1; however, the basal diet was a semipurified diet (0.98 mg B/kg diet). Diets were fed for 40 d; on d 40, blood samples were obtained for determination of plasma mineral and metabolite concentrations. Femurs were harvested from 8 pigs per treatment on d 40 for determination of mechanical properties, ash and lipid percentage. In Experiment 1, B did not affect performance, plasma minerals or metabolites or bone properties. In Experiment 2, B supplementation improved (P: < 0.05) the gain:feed ratio and increased plasma cholesterol and triglyceride concentrations. There was a treatment x sex interaction (P: < 0.05) in Experiment 2 for bone lipid to be lower and bending moment to be higher, with the response occurring in male pigs. Other dependent variables in Experiment 2 were not affected by treatment. In conclusion, B supplementation of a low B diet elicited responses of physiologic importance to pigs. However, B supplementation of a natural ingredient diet did not elicit a response.}, number={10}, journal={JOURNAL OF NUTRITION}, author={Armstrong, TA and Spears, JW and Crenshaw, TD and Nielsen, FH}, year={2000}, month={Oct}, pages={2575–2581} }
 @article{engle_spears_l._edens_2000, title={Dietary copper effects on lipid metabolism and circulating catecholamine concentrations in finishing steers}, volume={78}, DOI={10.2527/2000.78102737x}, abstractNote={Forty-eight Angus and Hereford x Angus steers were used to determine the effects of copper (Cu) on lipid and catecholamine metabolism. Steers were stratified by weight within breed and randomly assigned to treatments. Treatments consisted of 0 (control, no supplemental Cu), 10, or 40 mg of supplemental Cu (from Cu2(OH)3Cl)/kg DM. Steers were fed a corn silage-soybean meal-based growing diet for 42 d. Animals were then switched to a high-concentrate finishing diet and remained on the same dietary treatments. On d 70, indwelling jugular catheters were nonsurgically inserted into five steers per treatment. Blood samples were obtained from steers after a 24-h period of feed withdrawal, 1 h after feeding, and after i.v. administration of norepinephrine and were subsequently analyzed for nonesterified fatty acid (NEFA) and catecholamine concentrations. Average daily gain over the finishing period was higher (P < 0.06) in steers receiving supplemental Cu. Serum total cholesterol concentrations were reduced (P < 0.05) on d 84 and 112 in steers supplemented with Cu. Serum norepinephrine (P < 0.14) and NEFA concentrations following feed withdrawal tended (P < 0.12) to be higher in Cu-supplemented steers. Postfeeding norepinephrine concentrations tended to be higher (P < 0.14) in Cu-supplemented steers. Nonesterifled fatty acid concentrations were lower (P < 0.10) in Cu-supplemented steers after norepinephrine administration. Backfat depth was decreased (P < 0.10) and longissimus muscle polyunsaturated fatty acid percentages were increased (P < 0.10) in steers receiving supplemental Cu. These results indicate that Cu addition to a finishing diet containing 5 mg Cu/kg DM alters lipid metabolism. The reduction in backfat depth may be due to copper altering catecholamine metabolism in steers.}, number={10}, journal={Journal of Animal Science}, author={Engle, T. E. and Spears, J. W. and L. and Edens, F. W.}, year={2000}, pages={2737–2744} }
 @article{engel_spears_2000, title={Dietary copper effects on lipid metabolism, performance, and ruminal fermentation in finishing steers}, volume={78}, DOI={10.2527/2000.7892452x}, abstractNote={Sixty Angus steers (391.1+/-6.1 kg) were used to determine the effects of dietary Cu concentration on lipid metabolism and ruminal fermentation. Steers were stratified by weight and randomly assigned to treatments. Treatments consisted of 0 (control), 10, or 20 mg of supplemental Cu (as CuSO4)/kg diet DM. Steers were housed in pens equipped with individual electronic Calan gate feeders. On d 86 and 92, ruminal fluid was collected from two steers/treatment for IVDMD determination. Equal numbers of steers per treatment were slaughtered after receiving the finishing diets for 96 or 112 d. Gain, feed intake, feed efficiency, IVDMD, and ruminal VFA molar proportions were not affected by Cu supplementation. Copper supplementation increased (P < .05) liver Cu concentrations, and steers supplemented with 20 mg Cu/kg DM had higher (P < .05) liver Cu concentrations than steers supplemented with 10 mg Cu/kg DM. Serum total cholesterol concentrations were reduced by d 56 and at subsequent sampling dates in steers receiving supplemental Cu. Longissimus muscle cholesterol concentrations were lower (P < .10) in steers supplemented with Cu. Backfat depth was less (P < .05) in steers receiving supplemental Cu, but marbling scores were similar across treatments. Unsaturated fatty acid composition of longissimus muscle was increased (P < .05) and saturated fatty acid composition tended (P < .12) to be reduced in Cu-supplemented steers. Polyunsaturated fatty acid concentrations were higher (P < .05) in steers receiving Cu. These results indicate that addition of 10 or 20 mg Cu/kg to a high-concentrate diet containing 4.9 mg Cu/kg DM alters lipid and cholesterol metabolism in steers but does not affect ruminal fermentation.}, number={9}, journal={Journal of Animal Science}, author={Engel, T. E. and Spears, J. W.}, year={2000}, pages={2452–2458} }
 @article{armstrong_spears_heugten_engle_wright_2000, title={Effect of copper source (cupric citrate vs cupric sulfate) and level on growth performance and copper metabolism in pigs}, volume={13}, ISSN={["1011-2367"]}, DOI={10.5713/ajas.2000.1154}, number={8}, journal={ASIAN-AUSTRALASIAN JOURNAL OF ANIMAL SCIENCES}, author={Armstrong, TA and Spears, JW and Heugten, E and Engle, TE and Wright, CL}, year={2000}, month={Aug}, pages={1154–1161} }
 @article{luginbuhl_poore_spears_brown_2000, title={Effect of dietary copper level on performance and copper status of growing meat goats}, volume={16}, number={2000}, journal={Sheep & Goat Research Journal}, author={Luginbuhl, J. M. and Poore, M. H. and Spears, J. W. and Brown, T. T.}, year={2000}, pages={65–71} }
 @article{engle_spears_2000, title={Effects of dietary copper concentration and source on performance and copper status of growing and finishing steers}, volume={78}, number={9}, journal={Journal of Animal Science}, author={Engle, T. E. and Spears, J. W.}, year={2000}, pages={2446–2451} }
 @article{engle_spears_armstrong_wright_odle_2000, title={Effects of dietary copper source and concentration on carcass characteristics and lipid and cholesterol metabolism in growing and finishing steers}, volume={78}, DOI={10.2527/2000.7841053x}, abstractNote={We conducted an experiment to determine the effects of dietary copper (Cu) source and level on carcass characteristics, longissimus muscle fatty acid composition, and serum and muscle cholesterol concentrations in steers. Sixty Angus and Angus x Hereford steers were stratified by weight and initial liver Cu concentration within a breed and randomly assigned to treatments. Treatments consisted of: 1) control (no supplemental Cu); 2) 20 mg Cu/kg DM from Cu sulfate (CuSO4); 3) 40 mg Cu/kg DM from CuSO4; 4) 20 mg Cu/kg DM from Cu citrate; 5) 20 mg Cu/kg DM from Cu proteinate; and 6) 20 mg Cu/kg DM from tribasic Cu chloride. A corn silage-soybean meal-based diet was fed for 56 d. Steers were then switched to a high-concentrate diet. Equal numbers (n = 5) of steers per treatment were slaughtered after receiving the finishing diets for either 101 or 121 d. Serum cholesterol was not affected by treatment during the growing phase but was decreased (P < .05) in steers supplemented with Cu by d 84 of the finishing period and remained lower (P < . 05) at subsequent sampling periods. Longissimus muscle cholesterol concentration tended to be reduced (P < .11) by Cu supplementation. Hot carcass weight and backfat were lower (P < .05) in animals receiving supplemental Cu. However, Cu-supplemented and control steers had similar marbling scores. Longissimus muscle polyunsaturated fatty acid concentrations (18:2 and 18:3) were increased (P < .07) and saturated fatty acid concentrations tended (P < . 11) to be reduced by Cu supplementation. These results indicate that as little as 20 mg of supplemental Cu/kg diet can reduce backfat and serum cholesterol and increase muscle polyunsaturated fatty acids in steers fed high-concentrate diets.}, number={4}, journal={Journal of Animal Science}, author={Engle, T. E. and Spears, J. W. and Armstrong, T. A. and Wright, C. L. and Odle, J.}, year={2000}, pages={1053–1059} }
 @article{engle_spears_fellner_odle_2000, title={Effects of soybean oil and dietary copper on ruminal and tissue lipid metabolism in finishing steers}, volume={78}, DOI={10.2527/2000.78102713x}, abstractNote={An experiment was conducted to determine the effects of Cu and soybean oil (SBO) supplementation on ruminal and tissue lipid metabolism and carcass characteristics in finishing steers. Sixty Angus steers (369.0 +/- 10.1 kg) were stratified by weight and randomly assigned to treatments in a 2 x 2 factorial arrangement, with factors being 0 or 20 mg of supplemental Cu/kg DM from Cu sulfate and 0 or 4% SBO. Steers were fed a high-concentrate basal diet that contained 5.3 mg Cu/kg DM. Average daily gain and feed intake were reduced (P < 0.01) by SBO but were not affected by Cu. Gain:feed ratio was not affected by treatment. Liver Cu concentrations were higher (P < 0.01) in steers receiving supplemental Cu and lower (P < 0.04) in SBO-supplemented steers. Copper supplementation tended to reduce (P < 0.12) and SBO supplementation tended to increase (P < 0.11) serum cholesterol concentrations. Backfat depth was reduced (P < 0.10) by Cu and SBO supplementation. Marbling scores and longissimus muscle lipid content were not affected by Cu supplementation; however, SBO supplementation reduced (P < 0.01) marbling scores. Longissimus muscle polyunsaturated fatty acids tended to be increased (P < 0.14) in Cu-supplemented steers. Longissimus muscle C18-conjugated dienes and the 18:1 trans isomer were increased (P < 0.05) in SBO-supplemented steers. Ruminal fluid 18:3 was increased (P < 0.05) and the 18:1 trans isomer was decreased (P < 0.05) in Cu-supplemented steers. These results indicate that as little as 20 mg of supplemental Cu/kg DM can reduce backfat and may alter lipid metabolism in steers fed high-concentrate diets.}, number={10}, journal={Journal of Animal Science}, author={Engle, T. E. and Spears, J. W. and Fellner, Vivek and Odle, Jack}, year={2000}, pages={2713–2721} }
 @article{armstrong_williams_spears_schiffman_2000, title={High dietary copper improves odor characteristics of swine waste.}, volume={78}, ISSN={0021-8812}, url={http://dx.doi.org/10.2527/2000.784859x}, DOI={10.2527/2000.784859x}, abstractNote={We conducted two experiments to determine the effects of dietary copper concentration and source on odor characteristics of swine waste. In both experiments, 192 weanling gilts and barrows were allotted to 24 pens. Pens were randomly assigned to one of six dietary treatments, consisting of control (10 ppm Cu as cupric sulfate, CuSO4), 66 or 225 ppm Cu as CuSO4, or 33, 66, or 100 ppm Cu as cupric citrate (Cucitrate). An antibiotic was included in the diets for Exp. 1, but not Exp. 2. On d 28, fecal samples were randomly obtained from one pig per pen and stored at -20 degrees C until preparation and evaluation by an odor panel. The odor panel consisted of 10 individuals, and each panelist evaluated the odor intensity, irritation intensity, and odor quality of the samples. In Exp. 1, the odor and irritation intensity of the feces were lower (P < .05) from animals consuming diets containing 225 ppm Cu as CuSO4 and 66 or 100 ppm Cu as Cu-citrate compared to the control. The odor quality of the waste from animals consuming diets containing 225 ppm Cu as CuSO4 and 66 or 100 ppm Cu as Cu-citrate was improved (P < .05) compared to the 33 ppm Cu treatment. In Exp. 2, the odor intensity of the feces of pigs receiving diets supplemented with all concentrations of Cu-citrate was lower (P < .05) than that of feces from the control animals. Irritation intensity of the feces was not affected by treatment. Odor quality of waste of pigs supplemented with 225 ppm Cu from CuSO4 and all concentrations of Cu-citrate was improved (P < .05) compared to that of waste of the control pigs. Two gilts and two barrows from each nursery pen in Exp. 1 were continued through the growing-finishing phase on their respective experimental diets. The growing-finishing phase lasted 103 d, and fecal samples were randomly obtained from one pig per pen at the completion of the phase. During the growing-finishing phase, the odor intensity and the irritation intensity of the feces were lower (P < .05) from pigs supplemented with 66 and 225 ppm Cu as CuSO4 and 66 and 100 ppm Cu from Cu-citrate than from the control pigs. The odor quality of the waste was improved (P < .05) in all animals receiving supplemental Cu. These data indicate an improvement in odor characteristics of swine waste with the supplementation of Cu. In addition, lower concentrations of an organic nonsulfate Cu source resulted in similar odor characteristics of swine waste as 225 ppm CuSO4.}, number={4}, journal={Journal of Animal Science}, publisher={Oxford University Press (OUP)}, author={Armstrong, T A and Williams, C M and Spears, J W and Schiffman, S S}, year={2000}, pages={859} }
 @article{spears_2000, title={Micronutrients and immune function in cattle}, volume={59}, ISSN={["0029-6651"]}, DOI={10.1017/S0029665100000835}, abstractNote={Complex inter-relationships exist between certain micronutrients, immune function and disease resistance in cattle. Several micronutrients have been shown to influence immune responses. The relationship between deficiencies of some micronutrients and disease resistance is less clear. A number of studies have indicated that Cr supplementation may improve cell-mediated and humoral immune response as well as resistance to respiratory infections in stressed cattle. With respiratory-disease challenge models Cr generally does not affect disease resistance. Deficiencies of Cu, Se, vitamin E and Co in cattle reduce the ability of isolated neutrophils to kill yeast and/or bacteria. Cu deficiency reduces antibody production, but cell-mediated immunity is generally not altered. However, Cu deficiency appears to reduce production of interferon and tumour necrosis factor by mononuclear cells. Numerous studies have linked low vitamin E and/or Se status to increased susceptibility of dairy cows to intramammary infections. In contrast to findings in laboratory animals, marginal Zn deficiency does not appear to impair antibody production or lymphocyte responsiveness to mitogen stimulation in ruminants. Co deficiency has been associated with reduced resistance to parasitic infections. It is well documented that vitamin A-deficient animals are more susceptible to various types of infections. β-Carotene, possibly via its antioxidant properties, may affect immune function and disease resistance independent of its role as a precursor of vitamin A.}, number={4}, journal={PROCEEDINGS OF THE NUTRITION SOCIETY}, author={Spears, JW}, year={2000}, month={Nov}, pages={587–594} }
 @article{berg_croom_fernandez_spears_eisen_taylor_daniel_coles_boeheim_mannon_2000, title={Peptide YY administration decreases brain aluminum in the Ts65Dn Down syndrome mouse model}, volume={64}, number={1-2}, journal={Growth, Development, & Aging}, author={Berg, B. M. and Croom, J. and Fernandez, J. M. and Spears, J. W. and Eisen, E. J. and Taylor, I. L. and Daniel, L. R. and Coles, B. A. and Boeheim, F. and Mannon, P. J.}, year={2000}, pages={3–19} }
 @article{kegley_spears_1999, title={Chromium and cattle nutrition}, volume={12}, ISSN={["0896-548X"]}, DOI={10.1002/(SICI)1520-670X(1999)12:2<141::AID-JTRA11>3.0.CO;2-H}, abstractNote={Until recently, practical diets fed to cattle were assumed to provide sufficient chromium to meet requirements. Recent research now suggests that in some situations practical diets may not contain adequate chromium to maximize certain biological processes in ruminants. Supplementation of chromium has increased blood glucose clearance rates following intravenous infusions of glucose and/or insulin in some studies with calves. However, one experiment with lactating cows indicated that supplemental chromium decreased sensitivity to insulin. Differences in responses may reflect the energy balance of the animal. Early in lactation, cows are in a negative energy balance, whereas growing calves are in a positive energy balance. Supplemental chromium has increased milk production in first lactation cows. Gain and feed efficiency have been increased by supplementation of chromium in some experiments, but not in others. Lipid metabolism also has been affected by supplemental chromium. Lower concentrations of blood ketone bodies have been observed in cows supplemented with chromium. Chromium supplementation has not altered backfat thickness or increased lean composition of beef carcasses. Several forms of supplemental chromium have been investigated in cattle diets, including chromium nicotinic acid complex, chromium tripicolinate, high chromium yeast, amino acid-chelated chromium, and chromium chloride. Responses have varied between sources in the few studies where different supplemental sources have been compared. Presently, no supplemental chromium sources are approved for addition to cattle diets. One problem is that little is known regarding the bioavailability of chromium in feeds commonly used in cattle diets. Further research is needed to determine when supplementation of chromium will impact cattle performance. J. Trace Elem. Exp. Med. 12:141–147, 1999. © 1999 Wiley-Liss, Inc.}, number={2}, journal={JOURNAL OF TRACE ELEMENTS IN EXPERIMENTAL MEDICINE}, author={Kegley, EB and Spears, JW}, year={1999}, pages={141–147} }
 @article{engle_spears_brown_lloyd_1999, title={Effect of breed (Angus Vs Simmental) on immune function and response to a disease challenge in stressed steers and preweaned calves}, volume={77}, DOI={10.2527/1999.773516x}, abstractNote={Two experiments were conducted with feeder steer calves and preweaned calves to determine the effects of breed on immune response. In Exp. 1, newly weaned Angus (n = 24) and Simmental (n = 24) steer calves were blocked by weight within breed and randomly assigned to 12 pens with four calves per pen. The basal diet consisted of 87% corn silage (DM basis) and 13% of a soybean meal-mineral-vitamin supplement. Steers were allowed ad libitum access to feed throughout the study. On d 2 following weaning, calves received an intranasal inoculation of infectious bovine rhinotraecheitis virus (IBRV; 2.7 x 10(8) CCID50). Rectal temperatures in response to the IBRV were higher (P < .05) in Angus calves. On d 9, calves were injected i.m. with 10 mL of a 25% pig red blood cell (PRBC) suspension. Total immunoglobulin (Ig) and IgM titers against PRBC were higher (P < .05) for the Angus calves. Breed did affect cell-mediated immune response to phytohemagglutinin (PHA). In Exp. 2, preweaned (16 Angus and 16 Simmental) calves were selected based on breed, body weight, and sex. On 0 d, all selected calves were injected i.m. with 10 mL of a 25% PRBC suspension. Total Ig and IgG titers against PRBC were higher (P < .05) for Angus calves. On d 28, lymphocytes were isolated from peripheral blood obtained from eight calves per breed. Peripheral lymphocytes from the Angus calves had a greater (P < .07) blastogenic response to 6.25 microg/mL of PHA than lymphocytes from Simmental calves. Results indicate that the immune response of Angus and Simmental calves may differ.}, number={3}, journal={Journal of Animal Science}, author={Engle, T. E. and Spears, J. W. and Brown, T. T. and Lloyd, K. E.}, year={1999}, pages={516–521} }
 @article{spears_1999, title={Reevaluation of the metabolic essentiality of the minerals - Review}, volume={12}, ISSN={["1976-5517"]}, DOI={10.5713/ajas.1999.1002}, number={6}, journal={ASIAN-AUSTRALASIAN JOURNAL OF ANIMAL SCIENCES}, author={Spears, JW}, year={1999}, month={Sep}, pages={1002–1008} }
 @article{ward_spears_1999, title={The effects of low-copper diets with or without supplemental molybdenum on specific immune responses of stressed cattle}, volume={77}, DOI={10.2527/1999.771230x}, abstractNote={Angus bull calves (n = 42; 7 mo of age; 254 kg initial BW) were used to investigate the effects of dietary Cu and Mo on immune function of stressed cattle. Randomly selected calves (n = 22) were injected with 90 mg of Cu as Cu glycinate 28 d before weaning and castrated at weaning. These calves received 7.5 and 5 mg of supplemental Cu/kg of DM during a 41-d receiving phase and a 196-d growing phase, respectively. The remainder of the steers received no supplemental Cu during the experiment. Copper-supplemented steers had adequate Cu status at weaning, whereas unsupplemented calves were marginally Cu-deficient. Cell-mediated response to intradermal injection of phytohemagglutinin was not affected by dietary treatment during the receiving phase. During the growing phase, half of the steers in each Cu treatment were given 5 mg of supplemental Mo/kg of DM. Copper supplementation increased (P<.05) humoral response to ovalbumin injected on d 133 of the growing phase. On d 168 of the growing phase, calves receiving only supplemental Mo were severely Cu-deficient based on plasma and liver Cu concentrations. The other treatment groups had adequate Cu status. Before feeding on d 168 of the growing phase, half of the steers were loaded onto trailers and transported 2.5 h, and they remained on the trailers an additional 9.5 h. Humoral response to porcine erythrocytes (PRBC) and delayed-type hypersensitivity (DTH) to dinitrochlorobenzene was tested at the end of the stress period. There was a Cu x stress interaction for humoral response to PRBC, with Cu decreasing antibody titers in unstressed calves and increasing titers in stressed steers. Stressed steers had lower (P = .03) ADG during the 28 d following stress. The results of this study indicate that Cu deficiency and 5 mg of supplemental Mo/kg of DM do not dramatically alter the specific immunity of stressed cattle.}, number={1}, journal={Journal of Animal Science}, author={Ward, J. D. and Spears, J. W.}, year={1999}, pages={230–237} }
 @article{gengelbach_spears_1998, title={Effects of dietary copper and molybdenum on copper status, cytokine production, and humoral immune response of calves}, volume={81}, ISSN={["1525-3198"]}, DOI={10.3168/jds.S0022-0302(98)75893-X}, abstractNote={Twenty-four male Holstein calves were used to determine the effects of dietary Cu and Mo on performance, Cu status, and immune function of calves. Calves were fed a milk replacer that was deficient in Cu for 8 wk and then were randomly assigned after weaning to one of four treatments: 1) control (no supplemental Cu or Mo), 2) 10 mg of Cu (from CuSO4)/kg of dry matter (DM) (Cu diet), 3) 5 mg of Mo (from Na2MoO4)/kg of DM (Mo diet), or 4) 5 mg of Cu (from CuSO4) and 5 mg of Mo (from Na2MoO4)/kg of DM (Cu + Mo diet). The basal diet was a semipurified diet that contained approximately 1.1 mg of Cu and 1.1 mg of Mo/kg of DM. Calves fed the Cu and Mo diets gained weight more efficiently than those fed the control and Cu + Mo diets during the 112-d study. By d 84 of the study, calves fed the Cu diet had higher plasma Cu concentrations and plasma ceruloplasmin activities than did calves fed the other three diets and had higher liver Cu concentrations on d 136. Plasma and liver Cu concentrations did not differ among calves fed the control, Mo, and Cu + Mo diets. At d 112, activity of Cu-Zn superoxide dismutase was lower in calves fed the Mo diet than in calves fed the Cu diet. Serum total antibodies to porcine erythrocytes (primary response) were lower in calves fed the Mo diet than in calves fed the Cu diet at 7, 14, and 21 d postinoculation. Production of tumor necrosis factor and interleukin-1 by isolated peripheral blood monocytes was not significantly affected by treatment. Although no differences were apparent in plasma or liver Cu concentrations among calves fed the control, Mo, and Cu + Mo diets, calves fed the Mo diet had a more severe Cu deficiency based on depressed humoral immune response and superoxide dismutase activity.}, number={12}, journal={JOURNAL OF DAIRY SCIENCE}, author={Gengelbach, GP and Spears, JW}, year={1998}, month={Dec}, pages={3286–3292} }
 @article{droke_gengelbach_spears_1998, title={Influence of level and source (inorganic vs organic) of zinc supplementation on immune function in growing lambs}, volume={11}, ISSN={["1011-2367"]}, DOI={10.5713/ajas.1998.139}, number={2}, journal={ASIAN-AUSTRALASIAN JOURNAL OF ANIMAL SCIENCES}, author={Droke, EA and Gengelbach, GP and Spears, JW}, year={1998}, month={Apr}, pages={139–144} }
 @article{kegley_spears_brown_1997, title={Effect of shipping and chromium supplementation on performance, immune response, and disease resistance of steers}, volume={75}, DOI={10.2527/1997.7571956x}, abstractNote={Forty-eight Angus crossbred steers (263 +/- 2 kg initial BW) were blocked by weight and randomly assigned within weight group to treatment. Treatments consisted of control or .4 mg of supplemental Cr as Cr-nicotinic acid complex/kg of DM. Steers were fed diets containing 90% corn silage (DM basis) and 10% of a soybean meal-mineral-vitamin supplement. After 56 d on the dietary treatment, half of the steers in each treatment were transported 343 km and unloaded in an unfamiliar location. The next day, d 58, shipped steers were returned to the feedlot (50 km). On d 58 after shipped steers were returned to the feedlot, all steers were inoculated with infectious bovine rhinotracheitis virus (IBRV) intranasally. Average daily gain from d 0 to 80 was increased (P < .10) by supplemental Cr. There was a shipping x time interaction for serum cortisol concentrations. Shipping increased (P < .02) serum cortisol on d 58, but 7 d after transport there were no effects of shipping on serum cortisol. Transportation increased (P < .05) the ratio of neutrophils to lymphocytes. Supplemental Cr did not affect rectal temperature after the IBRV challenge or the antibody response to IBRV or porcine red blood cells. Immunoglobulin G antibody response to porcine red blood cells was decreased (P < .09) by shipping. Supplemental Cr as Cr-nicotinic acid improved ADG of growing steers, regardless of whether they had been stressed by shipping. Supplemental Cr did not affect any of the immune responses that were measured.}, number={7}, journal={Journal of Animal Science}, author={Kegley, E. B. and Spears, J. W. and Brown, T. T.}, year={1997}, pages={1956–1964} }
 @article{gengelbach_ward_spears_brown_1997, title={Effects of copper deficiency and copper deficiency coupled with high dietary iron or molybdenum on phagocytic cell function and response of calves to a respiratory disease challenge}, volume={75}, DOI={10.2527/1997.7541112x}, abstractNote={A study was conducted to determine the effects of supplementing a diet marginally deficient in copper (Cu) with iron (Fe), molybdenum (Mo), or Cu on phagocytic cell function and disease resistance of calves. Thirty-one calves were born to heifers fed a corn silage-based diet containing 4.5 mg of Cu/kg. Treatments consisted of 1) control (CON; no supplemental Cu, Fe, or Mo), 2) 600 mg of Fe added/kg (FE), 3) 5 mg of Mo added/kg (MO), or 4) 10 mg of Cu added/kg of DM (CU). Activity of superoxide dismutase was lower (P < .06) in neutrophils from MO vs CON or CU calves at 170 d of age. bactericidal activity of neutrophils from MO calves tended (P = .15) to be lower compared with those from CU calves at 70 d of age. Calves were inoculated intranasally with live infectious bovine rhinotracheitis virus (IBRV) 2 d after weaning, followed by intratracheal administration of Pasteurella hemolytica 5 d later. Iron- and Cu-supplemented calves exhibited higher (P < .01) body temperatures and lower (P < .06) feed intakes following IBRV inoculation compared with CON and MO calves. Copper-supplemented calves had higher levels of plasma tumor necrosis factor (TNF) than MO calves at weaning (P < .05) and tended to have higher plasma TNF (P = .11) than FE and MO calves 5 d after IBRV inoculation. These data indicate that dietary levels of Mo and Cu can affect body temperature and feed intake responses to disease by affecting TNF and perhaps other cytokines.}, number={4}, journal={Journal of Animal Science}, author={Gengelbach, G. P. and Ward, J. D. and Spears, J. W. and Brown, T.T.}, year={1997}, pages={1112–1118} }
 @article{heugten_spears_1997, title={Immune response and growth of stressed weanling pigs fed diets supplemented with organic or inorganic forms of chromium}, volume={75}, DOI={10.2527/1997.752409x}, abstractNote={A 2 x 4 factorial arrangement of treatments was used in a randomized complete block designed study to determine the effects of chromium level and source on growth and immune response of stressed and non-stressed 3-wk-old crossbred weanling pigs (BW was 6.35 kg). Factors included 1) immune stress or control and 2) no supplemental Cr or .2 ppm of supplemental Cr from either CrCl3, Cr-picolinate, or Cr-nicotinic acid complex. The basal diet was a corn-soybean meal-whey diet containing 1.2% lysine. Escherichia coli lipopolysaccharide (LPS) was the stress-inducing agent and was injected on d 7, 10, and 13 of the experiment. Immune challenge with LPS resulted in reduced gain (P < .05) and feed intake (P < .10). Supplementation with Cr was not effective in alleviating the depression in growth due to LPS. However, supplementation of control pigs with Cr tended to improve (P < .10) gain and feed intake. In vitro cellular immune response as measured by a lymphocyte blastogenesis assay was increased (P < .10) in pigs fed supplemental Cr from CrCl3, or Cr-picolinate. Antibody response to sheep red blood cells tended to be increased (P < .10) in pigs supplemented with Cr-nicotinic acid, but antibody response to ovalbumin was decreased (P < .05) in pigs supplemented with organic forms of Cr. At the end of the study, effects of Cr supplementation on lymphocyte proliferative response were investigated before and after ACTH administration. Injections of ACTH resulted in increased (P < .001) serum cortisol levels and increased lymphocyte proliferation. Supplementation of Cr did not affect lymphocyte blastogenic response before or after ACTH injection (P > .10). These data suggest that Cr supplementation was not beneficial during immune stress in pigs.}, number={2}, journal={Journal of Animal Science}, author={Heugten, Eric and Spears, J.W.}, year={1997}, pages={409–416} }
 @article{ward_spears_1997, title={Long-term effects of consumption of low-copper diets with or without supplemental molybdenum on copper status, performance, and carcass characteristics of cattle}, volume={75}, DOI={10.2527/1997.75113057x}, abstractNote={We used 42 Angus bull calves (7 mo of age) to determine long-term effects of low Cu diets with or without supplemental Mo on performance, carcass characteristics, and Cu status. Twenty-two bulls were injected with 90 mg of Cu 28 d before weaning. After weaning, injected steers were fed a diet supplemented with 7.5 mg of Cu/kg of DM; control steers received no supplemental Cu. At the end of the 40-d receiving phase, supplemental Cu was reduced to 5 mg/kg of DM. One half of the steers in each group were fed 5 mg of supplemental Mo/kg of DM following the receiving phase. The growing phase lasted 196 d. Steers were then switched to a high concentrate finishing diet for 49 d. Copper injection increased (P < .01) plasma Cu concentrations at weaning, and Cu-supplemented steers had greater (P < .05) plasma Cu, ceruloplasmin, superoxide dismutase activity (SOD), and liver Cu at the beginning of the growing phase. Supplemental Mo depressed plasma Cu, ceruloplasmin, and SOD during the growing and finishing phases in non-Cu-supplemented but not in Cu-supplemented steers. Copper supplementation increased DMI during the receiving (P < .05) and growing (P < .08) phases and increased (P < .08) ADG and gain:feed ratios during the finishing phase. Steers fed supplemental Cu produced carcasses with less (P < .06) backfat and slightly larger (P < .09) rib eye areas. The results of this experiment suggest that dietary Cu concentrations may alter cattle performance and carcass characteristics.}, number={11}, journal={Journal of Animal Science}, author={Ward, J. D. and Spears, J. W.}, year={1997}, pages={3057–3065} }
 @article{kegley_spears_eisemann_1997, title={Performance and glucose metabolism in calves fed a chromium-nicotinic acid complex or chromium chloride}, volume={80}, ISSN={["0022-0302"]}, DOI={10.3168/jds.S0022-0302(97)76107-1}, abstractNote={Twenty-four Holstein bull calves were fed a milk replacer diet to assess the effects of Cr on calf performance and metabolism of glucose. Treatments consisted of no supplemental Cr (control) or 0.4 mg/kg of dry matter of supplemental Cr from CrCl3 or from a Cr-nicotinic acid complex. Supplementation with the Crt-nicotinic acid complex increased the average daily gain and feed efficiency from d 28 to 42, but not over the entire 63-d performance phase. Calves that were fed diets supplemented with CrCl3 or the Cr-nicotinic acid complex had lower plasma glucose concentrations at 45 to 180 min after an i.v. infusion of insulin than did controls. Calves fed diets supplemented with the Cr-nicotinic acid complex also had lower plasma glucose concentrations from 90 to 180 min after insulin challenge than did calves that were fed diets supplemented with CrCl3. After an i.v. infusion of glucose, calves that were fed diets supplemented with CrCl3 had lower serum insulin concentrations at 10 to 25 min after challenge than did controls or calves that were fed diets supplemented with the Cr-nicotinic acid complex. However, the glucose clearance rate after glucose infusion was not affected by Cr supplementation. Chromium supplementation did not markedly affect the performance of calves, but the Cr-nicotinic acid complex and CrCl3 did intensify the response to insulin administered i.v.}, number={8}, journal={JOURNAL OF DAIRY SCIENCE}, author={Kegley, EB and Spears, JW and Eisemann, JH}, year={1997}, month={Aug}, pages={1744–1750} }
 @inproceedings{spears_1997, title={Relationship between nutrition and immune response}, number={1997}, booktitle={Tri-state dairy nutrition conference. Proceedings. Sponsored by Michigan State University, Purdue University, and Ohio State University, 1997}, author={Spears, J. W.}, year={1997}, pages={1–11} }
 @article{ward_gengelbach_spears_1997, title={The effects of copper deficiency with or without high dietary iron or molybdenum on immune function of cattle}, volume={75}, DOI={10.2527/1997.7551400x}, abstractNote={Two experiments were conducted to determine the effects of Cu deficiency with or without high dietary Mo or Fe on the specific immunity of calves. In Exp. 1, calves from 38 bred heifers, fed corn silage-based experimental diets from the last third of gestation until the calves were weaned, were used. Dietary treatments were control (no supplemental Fe, Mo, or Cu), 600 mg of supplemental Fe/kg of DM, 5 mg of supplemental Mo/kg of DM, and 10 mg of supplemental Cu/kg of DM. In Exp. 2, 18 Holstein bull calves were fed commercial milk replacer low in Cu for 49 d and then fed semipurified diets containing approximately 1.1 mg of Cu/kg of DM or diets supplemented with 5 mg of Mo or 10 mg of Cu per kilogram of DM for 126 d. Feeding diets not supplemented with Cu resulted in severe Cu deficiency in both experiments. During Exp. 1, control calves had higher (P < .10) secondary antibody response to pig erythrocytes than Cu-, Mo-, and Fe-supplemented calves. During Exp. 2, in vitro Cu supplementation decreased (P < .01) lymphocyte blastogenic response. In vivo cell-mediated response to phytohemagglutinin was decreased (P < .10) by Cu supplementation during Exp. 1 but was increased (P < .10) by Cu and Mo supplementation during Exp. 2. Copper deficiency and Cu deficiency coupled with high dietary Mo or Fe produced inconsistent immune function responses, indicating that Cu deficiency may not affect specific immune function of calves.}, number={5}, journal={Journal of Animal Science}, author={Ward, J. D. and Gengelbach, G. P. and Spears, J. W.}, year={1997}, pages={1400–1408} }
 @article{spears_1996, title={Beef nutrition in the 21st century}, volume={58}, ISSN={["0377-8401"]}, DOI={10.1016/0377-8401(95)00871-3}, abstractNote={Consumer demand for a leaner product will drive to some extent how finishing cattle are fed in the 21st century. A major challenge is to produce a leaner product while maintaining the flavor characteristics desired in quality beef. Several compounds are currently being evaluated that increase lean and reduce fat and if these compounds are approved for use in cattle, requirements of certain nutrients will likely be affected. Environmental pressures to reduce the excretion of nitrogen and phosphorus and decrease the loss of methane from the rumen will also affect how cattle are fed in the future. Requirements for many minerals are poorly defined but hopefully by early in the 21st century our knowledge of requirements and factors that affect requirements for specific minerals will become more complete, allowing nutritionists to better formulate mineral supplements to meet animal requirements. Feedlot diets will likely be formulated for a specific cation-anion balance. The amount of grain used in cattle diets in the future will depend on the cost of cereal grains. Molecular biology techniques offer potential for improving forage quality in the future. Considerable potential also exists for improving the digestibility of low quality fibrous feeds by ruminants via various chemical treatments. It may be possible through genetic engineering technologies to enhance the ability of certain rumen microorganisms to digest fiber by introducing appropriate genes. Finally, the use of nutrients to enhance immunity and thus prevent disease will become increasingly important in the future because of increasing pressure to restrict the use of antibiotics to treat or prevent disease.}, number={1-2}, journal={ANIMAL FEED SCIENCE AND TECHNOLOGY}, author={Spears, JW}, year={1996}, month={Apr}, pages={29–35} }
 @article{spears_1996, title={Organic trace minerals in ruminant nutrition}, volume={58}, ISSN={["0377-8401"]}, DOI={10.1016/0377-8401(95)00881-0}, abstractNote={This paper defines the various types (complexes, amino acid chelates and proteinates) of organic trace minerals commercially available and reviews research regarding their bioavailability and effects on physiological responses in ruminants. The addition of one or more organic trace minerals to cattle diets has increased growth, milk production, reproduction and/or immune response in some studies. It is not possible to determine from some of the studies if the responses observed were due to the organic mineral(s) per se or simply to increased dietary mineral intake. Zinc methionine has been studied to the greatest extent of any of the chelated or metal complex products available. The mode of action of trace mineral chelates or complexes is largely unknown. Based on apparent absorption or tissue and blood concentrations, little evidence is available to suggest that organic trace minerals are considerably better absorbed than inorganic forms. In explaining the beneficial responses to certain organic trace minerals, the quantity of mineral absorbed may not be as important as the form of the mineral absorbed. Further studies with organic trace minerals are needed to better define conditions where performance or health responses may be expected and to determine the mode of action whereby organic trace mineral supplements improve ruminant performance.}, number={1-2}, journal={ANIMAL FEED SCIENCE AND TECHNOLOGY}, author={Spears, JW}, year={1996}, month={Apr}, pages={151–163} }
 @article{spears_1994, title={Minerals in forages}, ISBN={0891181199}, DOI={10.2134/1994.foragequality.c7}, abstractNote={Forages provide an important source of minerals for ruminants. Bioavailability of forage minerals to ruminants may be affected by the distribution of minerals within the forage and the chemical form of the elements present. The ability of a forage to provide animals with an adequate supply of minerals is dependent on the mineral content and also the bioavailability of the mineral. The concentration of individual minerals in forages varies greatly depending on soil, plant, and management factors. Certain minerals can affect forage quality. A number of minerals have been found to be associated with the plant cell wall. Only small amounts of phosphorus, sulfur, potassium, and magnesium were located in the cell wall while larger quantities of calcium, manganese, zinc, and copper were present. Increased knowledge of mineral requirements and availability of minerals from forages in the future will allow for formulation of mineral supplements that maximize ruminant performance.}, journal={Forage quality, evaluation, and utilization}, publisher={Madison, Wis., USA : American Society of Agronomy, Inc., Crop Science Society of America, Inc., and Soil Science Society of America, Inc}, author={Spears, J. W.}, year={1994}, pages={281} }
 @article{haven_wichtel_bristol_fetrow_spears_1992, title={The effects of antibiotic prophylaxis on postoperative complications after rumenotomy in cattle}, volume={200}, number={9}, journal={Journal of the American Veterinary Medical Association}, author={Haven, M. L. and Wichtel, J. J. and Bristol, D. G. and Fetrow, J. F. and Spears, J. W.}, year={1992}, pages={1332–1335} }
 @article{spears_harvey_brown_1991, title={Effects of zinc methionine and zinc oxide on performance, blood characteristics, and antibody titer response to viral vaccination in stressed feeder calves}, volume={199}, number={12}, journal={Journal of the American Veterinary Medical Association}, author={Spears, J. W. and Harvey, R. W. and Brown, T. T., Jr.}, year={1991}, pages={1731} }
 @article{spears_1990, title={IONOPHORES AND NUTRIENT DIGESTION AND ABSORPTION IN RUMINANTS}, volume={120}, ISSN={["1541-6100"]}, DOI={10.1093/jn/120.6.632}, abstractNote={This paper reviews the effects of feeding ionophores on nutrient digestion and absorption. In cattle, monensin and lasalocid increase apparent digestible energy by an average of 2.0 percentage units. In sheep, responses in digestible energy to ionophore feeding have been more variable, and neither monensin nor lasalocid have, on average, affected digestible energy. The effect of ionophores on fiber digestibility appears to depend on diet composition and source of fiber because both increases and decreases in fiber digestibility have been associated with ionophore feeding. Lasalocid and monensin reduce the percentage of starch digested in the rumen and increase the quantity of starch digested in the intestine. However, total gastrointestinal tract digestion of starch has generally not been affected by ionophores. Apparent nitrogen digestibility has been increased by ionophore feeding in a number of animal species. Apparent absorption of magnesium, phosphorus, zinc and selenium has been increased by ionophore supplementation. Absorption of calcium, potassium and sodium has been inconsistently affected by ionophores. Possible mechanisms whereby ionophores may affect nutrient digestion and absorption are discussed.}, number={6}, journal={JOURNAL OF NUTRITION}, author={SPEARS, JW}, year={1990}, month={Jun}, pages={632–638} }
 @article{spears_schricker_burns_1989, title={Influence of lysocellin and monensin on mineral metabolism of steers fed forage-based diets}, volume={67}, DOI={10.2527/jas1989.6782140x}, abstractNote={Studies were conducted to determine the effects of lysocellin and monensin on mineral metabolism of steers fed forage-based diets. In each study treatments consisted of 1) control, 2) 100 mg lysocellin/d, 3) 200 mg lysocellin/d and 4) 200 mg monensin/d. Twenty-four growing Hereford steers were used in each of two experiments to evaluate the effects of ionophore feeding on plasma and ruminal soluble mineral concentrations. Steers were fed individually greenchop (tall fescue and bermudagrass) ad libitum and .91 kg/d of a corn-trace mineral salt-ionophore supplement. Plasma and ruminal fluid samples were obtained on d 28 and 84 in both studies. Ruminal concentrations of soluble phosphorus (P) and iron (Fe) were higher (P less than .05), whereas soluble manganese (Mn) was lower (P less than .01), in steers fed lysocellin than in controls. Steers fed lysocellin had higher (P less than .05) plasma magnesium (Mg) concentrations than control steers. Plasma and ruminal soluble mineral concentrations generally were similar for the monensin and 200 mg lysocellin treatments. Two additional studies were conducted to determine the effects of lysocellin and monensin on macromineral apparent absorption and retention in steers fed tall fescue greenchop. Steers were adjusted to their diets for 28 d and then placed in metabolism crates for a 6-d acclimation followed by a 5-d collection of urine and feces. Percent apparent absorption of calcium (Ca), potassium (K), Mg and P was higher (P less than .05), whereas sodium (Na) absorption was lower (P less than .05), in steers fed lysocellin than in controls. Mineral absorption was similar in steers fed 200 mg lysocellin or monensin. Calcium (P less than .05) and K (P less than .10) retention (percent of intake) was increased by ionophore feeding. Results indicate that lysocellin and monensin alter apparent absorption and retention of certain minerals in steers fed forage-based diets.}, number={8}, journal={Journal of Animal Science}, author={Spears, J. W. and Schricker, B. R. and Burns, J. C.}, year={1989}, pages={2140} }
 @article{spears_burns_wolfrom_1989, title={Lysocellin effects on growth performance, ruminal fermentation, nutrient digestibility and nitrogen metabolism in steers fed forage diets}, volume={67}, DOI={10.2527/jas1989.672547x}, abstractNote={Studies were conducted to determine the effects of lysocellin on growth performance and metabolism of steers fed forage-based diets. Treatments in all experiments consisted of 1) control, 2) 100 mg lysocellin/d, 3) 200 mg lysocellin/d and 4) 200 mg monensin/d. In each of two 90-d performance studies, 24 Hereford steers were individually fed greenchop (fungus-free tall fescue and Coastal and Tifton-44 bermudagrass) ad libitum and .91 kg/d of a corn-trace mineral salt supplement. In Exp. 1, tall fescue was fed from d 1 to 45 and bermudagrass from d 46 to 90. Bermudagrass was offered during d 1 to 45 and tall fescue during d 46 to 90 in Exp. 2. Lysocellin improved gain (Exp. 1, P less than .01) and feed conversion (Exp. 1 and 2 combined, P less than .05), decreased total VFA concentrations (P less than .05), increased molar proportions of propionate, isobutyrate and isovalerate (P less than .01), decreased molar proportions of acetate and butyrate (P less than .01) and lowered acetate:propionate (P less than .01). Two metabolism studies involving a total of 16 Hereford steers were conducted. Steers were fed tall fescue greenchop and .91 kg/d supplement for a 34-d adjustment period followed by a 5-d total collection period. Lysocellin increased N digestibility (P less than .01) and N retention (P less than .06) but did not (P greater than .05) affect DM, NDF or ADF digestibility. Data indicate that lysocellin results in major alterations in ruminal fermentation and can increase growth performance and N retention in steers fed forage-based diets.}, number={2}, journal={Journal of Animal Science}, author={Spears, J. W. and Burns, J. C. and Wolfrom, G. W.}, year={1989}, pages={547} }
 @article{spears_1989, title={Zinc methionine for ruminants: Relative bioavailability of zinc in lambs and effects of growth and performance of growing heifers}, volume={67}, DOI={10.2527/jas1989.673835x}, abstractNote={Studies were conducted to evaluate zinc methionine (ZnMet) as a source of Zn for ruminants. Experiment 1 compared the availability of Zn in ZnMet and zinc oxide (ZnO) in lambs fed a semi-purified diet deficient in Zn. Based on growth rate and animal performance, plasma Zn and plasma alkaline phosphatase activity, no differences in Zn availability were detected between the two Zn sources. Apparent absorption of Zn also was similar, but Zn retention was higher (P less than .01) in lambs fed ZnMet because of a tendency for lower urinary Zn excretion (P less than .19) in this group. Zinc absorption and retention by lambs were similar for the two Zn sources in Exp. 2 when 20 mg Zn/kg was added to an orchardgrass hay-based diet containing 30 mg Zn/kg. In Exp. 3, lambs were dosed orally with 300 mg of Zn as ZnO or ZnMet, and the increase in plasma Zn following dosing was monitored. The increase in plasma Zn above predosing values was similar at 6 h but was higher at 12 (P less than .10) and 24 h (P less than .05) postdosing in lambs given ZnMet. Thirty-six Hereford x Simmental heifers (271 kg) were used in Exp. 4 to determine the influence of supplementing Zn (25 mg/kg) as ZnO or ZnMet of growth performance and Zn status. Heifers were fed a corn silage-based diet that contained 23.1 mg Zn/kg during the 126-d study. Zinc supplementation to the basal diet increased (P less than .05) gain and feed/gain during the first 56 d, but not for the entire 126-d study.(ABSTRACT TRUNCATED AT 250 WORDS)}, number={3}, journal={Journal of Animal Science}, author={Spears, J. W.}, year={1989}, pages={835} }
 @article{spears_harvey_1984, title={PERFORMANCE, RUMINAL AND SERUM CHARACTERISTICS OF STEERS FED LASALOCID ON PASTURE}, volume={58}, ISSN={["1525-3163"]}, DOI={10.2527/jas1984.582460x}, abstractNote={Seventy-two growing steers were used in a 126-d study to determine the influence of varying levels of lasalocid on performance, ruminal and serum characteristics of animals grazing pasture. Treatments consisted of: 1) control; 2) 200 mg lasalocid/d and 3) 300 mg lasalocid/d. Each treatment was replicated three times and each replicate of eight steers was maintained on 3.0 ha of pasture. Pastures consisted of a mixture of tall fescue, orchard grass and ladino clover. In addition to pasture, each replicate of steers was group fed ground corn at a rate of .91 kg X head-1 X d-1 with the lasalocid incorporated into the grain. Average daily gains were .50, .60 and .57 kg, respectively, for steers on the control, and for the 200 and 300 mg lasalocid treatments, which differed (P less than .05) from controls. Ruminal acetate (mol/100 mol) was lower (P less than .05) in steers fed lasalocid at 28 d, but similar for all treatments at 56 and 112 d. Molar proportion of propionate was higher (P less than .05) and butyrate and valerate were lower (P less than .10) in rumen fluid of steers receiving 200 or 300 mg/d of lasalocid. Plasma glucose concentrations were similar for controls and steers receiving 200 mg lasalocid/d, but higher (P less than .05) in steers fed 300 mg lasalocid/d. Serum Mg concentrations were lower (P less than .01) in steers receiving lasalocid. Potassium concentrations in serum were slightly lower (P less than .01) in animals fed lasalocid at 112 d, but not at 28 or 56 d.(ABSTRACT TRUNCATED AT 250 WORDS)}, number={2}, journal={JOURNAL OF ANIMAL SCIENCE}, author={SPEARS, JW and HARVEY, RW}, year={1984}, pages={460–464} }