@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={Journal Article Effect of zinc source and concentration and chromium supplementation on performance and carcass characteristics in feedlot steers,, Get access Ashley M Budde, Ashley M Budde Department of Animal Sciences, Colorado State University, Fort Collins, CO Search for other works by this author on: Oxford Academic PubMed Google Scholar Karen Sellins, Karen Sellins Department of Animal Sciences, Colorado State University, Fort Collins, CO Search for other works by this author on: Oxford Academic PubMed Google Scholar Karen E Lloyd, Karen E Lloyd North Carolina State University, Raleigh, NC Search for other works by this author on: Oxford Academic PubMed Google Scholar John J Wagner, John J Wagner Department of Animal Sciences, Colorado State University, Fort Collins, CO Search for other works by this author on: Oxford Academic PubMed Google Scholar Jeff S Heldt, Jeff S Heldt Micronutrients USA LLC, Indianapolis, IN Search for other works by this author on: Oxford Academic PubMed Google Scholar Jerry W Spears, Jerry W Spears North Carolina State University, Raleigh, NC Search for other works by this author on: Oxford Academic PubMed Google Scholar Terry E Engle Terry E Engle Department of Animal Sciences, Colorado State University, Fort Collins, CO Corresponding author: terry.engle@colostate.edu. Search for other works by this author on: Oxford Academic PubMed Google Scholar Journal of Animal Science, Volume 97, Issue 3, March 2019, Pages 1286–1295, https://doi.org/10.1093/jas/skz016 Published: 10 January 2019 Article history Received: 15 October 2018 Accepted: 07 January 2019 Published: 10 January 2019}, 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{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{gill_lloyd_bowman_siciliano_pratt-phillips_2017, title={Relationships Among Digestible Energy Intake, Body Weight, and Body Condition in Mature Idle Horses}, volume={54}, ISSN={["1542-7412"]}, DOI={10.1016/j.jevs.2017.02.017}, abstractNote={The objective of this study was to evaluate the relationships among digestible energy (DE) intake, body weight (BW), and body condition score (BCS) in lean/moderate condition horses. The feed intake of 35 Quarter Horses (age 5.3 ± 1.2 years; BW 462 ± 39 kg; BCS 4.5 ± 0.5) was recorded daily over three, 42-day feeding trials. Horses were offered 1.75–2.00 kg DM/100 kg BW in Orchard grass hay and 0.2 kg/100 kg BW in whole oats. Body weight and BCS were recorded biweekly. Daily DE intake was calculated according to Pagan and recorded as the amount fed minus any refusal. The daily kilogram intake was multiplied by the DE (Mcal/kg) content of the feed to equal the total calories per day. The mean within-horse ΔBW and ΔBCS from 0 to 42 days of each trial were evaluated using paired t tests. Trial 1 horses consumed 24.5 Mcal/d and BW increased (P < .001) by 24 ± 3 kg; however, there was no significant change in BCS (0.0 ± 0.5). Trial 2 horses consumed 22.8 Mcal/d and BW increased (P = .009) by 8 ± 3 kg and BCS tended to increase (P = .06) by 0.5 ± 0.5. Trial 3 horses consumed 25.7 Mcal/d and BW and BCS increased (P < .001) by 22 ± 2 kg and 1.0 ± 0.5, respectively. According to trial, horses required approximately 19, 34, and 18 Mcal/kg of weight gain, respectively. Additional factors affecting weight gain are related to the individual.}, journal={JOURNAL OF EQUINE VETERINARY SCIENCE}, author={Gill, Jennifer Christine and Lloyd, Karen Elizabeth and Bowman, Morghan and Siciliano, Paul David and Pratt-Phillips, Shannon Elizabeth}, year={2017}, month={Jul}, pages={32–36} }
 @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{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{huang_yang_xiao_lloyd_lin_2015, title={Effects of Supplemental Chromium Source and Concentration on Growth Performance, Carcass Traits, and Meat Quality of Broilers Under Heat Stress Conditions}, volume={170}, ISSN={0163-4984 1559-0720}, url={http://dx.doi.org/10.1007/s12011-015-0443-z}, DOI={10.1007/s12011-015-0443-z}, number={1}, journal={Biological Trace Element Research}, publisher={Springer Science and Business Media LLC}, author={Huang, Yanling and Yang, Jian and Xiao, Fang and Lloyd, Karen and Lin, Xi}, year={2015}, month={Jul}, pages={216–223} }
 @article{zheng_huang_xiao_lin_lloyd_2015, title={Effects of Supplemental Chromium Source and Concentration on Growth, Carcass Characteristics, and Serum Lipid Parameters of Broilers Reared Under Normal Conditions}, volume={169}, ISSN={0163-4984 1559-0720}, url={http://dx.doi.org/10.1007/s12011-015-0419-z}, DOI={10.1007/s12011-015-0419-z}, number={2}, journal={Biological Trace Element Research}, publisher={Springer Science and Business Media LLC}, author={Zheng, Cancai and Huang, Yanling and Xiao, Fang and Lin, Xi and Lloyd, Karen}, year={2015}, month={Jul}, pages={352–358} }
 @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{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{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{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 NH4SO4) supplemented at 0, 0.15, or 0.30% of DM, and NaHCO3 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 NaHCO3, 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{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={Thirty-six Angus and Angus x Simmental cross steers (initial BW 269.5 +/- 22.3 kg) were used to determine the effects of dietary boron (B) on performance and immune function. Steers were fed on one of the three dietary treatments: (i) control (no supplemental B; 7.2 mg B/kg DM), (ii) 5 mg supplemental B/kg DM and (iii) 50 mg supplemental B/kg DM, from sodium borate for 78 days. Supplementation of dietary B had no effect on body weight (BW) gain, feed intake or gain:feed during the study. Jugular blood samples were collected prior to feeding on days 28, 63 and 77 for plasma-B analysis. Supplementation of dietary B increased (p < 0.001) plasma B-concentration in a dose-responsive manner. Furthermore, plasma B-concentration was correlated (p < 0.001; R(2) = 0. 95) to daily B-intake (mg B/day). Jugular blood was also collected, from an equal number of steers from each treatment, on day 42 or 44 for determination of in vitro production of interferon-gamma and tumour necrosis factor-alpha from isolated monocytes and assessment of lymphocyte proliferation. Dietary B did not affect T- or B-lymphocyte proliferation or in vitro cytokine production from monocytes. On day 49 of the study, the humoral immune response was assessed by i.m. injection of a 25% pig red blood cell (PRBC) solution for determination of anti-PRBC IgG and IgM titre responses. Boron-supplemented steers had greater (p = 0.035) anti-PRBC IgG titres than controls on day 7 but not on day 14 or 21 post-injection. Anti-PRBC IgM titres did not differ throughout the sampling period. Results from this study indicate that supplemental B had minimal effects on immune function and did not affect performance of growing steers.}, 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{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 calves v. − 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 calves v. − 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 (CuSO4) 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 CuSO4, 3) 10 mg of Cu/kg of DM from CuSO4, 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 CuSO4 (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 CuSO4 (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 CuSO4 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_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{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{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 MnSO4. 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{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{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{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{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{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{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_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 × 108 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 µ/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} }