@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{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{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_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 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} }