@article{budde_sellins_lloyd_wagner_heldt_spears_engle_2019, title={Effect of zinc source and concentration and chromium supplementation on performance and carcass characteristics in feedlot steers}, volume={97}, ISSN={["1525-3163"]}, DOI={10.1093/jas/skz016}, abstractNote={Four hundred crossbred steers were used in a randomized complete block design to investigate the effects of supplemental Zn source and concentration, and dietary Cr on performance and carcass characteristics of feedlot steers fed a steam-flaked corn-based finishing diet. Steers were blocked by initial BW within cattle source (3 sources) and randomly assigned within block to 1 of 5 treatments. Before the initiation of the experiment, trace mineral supplement sources were analyzed for Zn and Cr. Zinc and Cr concentrations of the Zn sources were used to balance all dietary treatments to obtain correct Zn and Cr experimental doses. Treatments were the addition of: 1) 90 mg Zn/kg DM from ZnSO4 and 0.25 mg Cr/kg DM from Cr propionate (90ZS+Cr); 2) 30 mg Zn/kg DM from Zn hydroxychloride and 0.25 mg Cr/kg DM from Cr propionate (30ZH+Cr); 3) 90 mg Zn/kg DM from Zn hydroxychloride and 0.25 mg Cr/kg DM from Cr propionate (90ZH+Cr); 4) 60 mg Zn/kg DM from ZnSO4 and 30 mg Zn/kg DM from Zn methionine (90ZSM); and 5) 90 mg Zn/kg DM from Zn hydroxychloride (90ZH). Steers were individually weighed on d-2 and on 2 consecutive days at the end of the experiment. Initial liver biopsies were obtained from all steers at processing. Equal numbers of pen replicates per treatment were slaughtered at a commercial abattoir on day 162, 176, and 211; individual carcass data and final liver samples were collected. Total finishing dietary Zn and Cr concentrations were 118.4, 58.2, 114.2, 123.0, and 108.2 mg Zn/kg DM and 0.740, 0.668, 0.763, 0.767, and 0.461 mg Cr/kg DM, for treatments 1 to 5, respectively. Data were analyzed statistically using preplanned single degree of freedom contrasts. Steers receiving 90ZH+Cr had greater final BW (P < 0.04) and ADG (P < 0.03) when compared with steers receiving 90ZH. Additionally, hot carcass weight was 8.5 kg greater (P < 0.03) for 90ZH+Cr compared with 90ZH supplemented steers. Steers receiving 90ZH+Cr had greater longissimus muscle area when compared with steers receiving 90ZSM. Dry matter intake, G:F, morbidity and mortality, and all other carcass measurements were similar across treatments. These data indicate that under the conditions of this experiment, Zn source and concentration had no impact on live performance, liver Zn and Cu concentrations, and carcass characteristics. Supplemental Cr in diets containing 90 mg of supplemental Zn/kg DM from ZH improved final BW, ADG, and hot carcass weights.}, number={3}, journal={JOURNAL OF ANIMAL SCIENCE}, author={Budde, Ashley M. and Sellins, Karen and Lloyd, Karen E. and Wagner, John J. and Heldt, Jeff S. and Spears, Jerry W. and Engle, Terry E.}, year={2019}, month={Mar}, pages={1286–1295} }
 @article{creech_spears_flowers_hill_lloyd_armstrong_engle_2004, title={Effect of dietary trace mineral concentration and source (inorganic vs. chelated) on performance, mineral status, and fecal mineral excretion in pigs from weaning through finishing}, volume={82}, DOI={10.2527/2004.8272140x}, abstractNote={Two hundred and sixteen weanling gilts (6.65+/-0.08 kg) were used to determine the effects of decreasing supplemental concentrations of Zn, Cu, Fe, and Mn, and trace mineral source (inorganic vs. chelated) on growth performance, mineral status, and fecal mineral concentrations from weaning through development. The study was conducted over three trials with 72 pigs in each trial. Gilts were blocked by weight and randomly assigned to either 1) control, 2) reduced inorganic, or 3) reduced chelated trace minerals. The control diet was supplemented with 25, 150, 180, and 60 mg/kg of Cu, Zn, Fe, and Mn (in sulfate forms), respectively, during the nursery phase and 15, 100, 100, and 40 mg/kg of supplemental Cu, Zn, Fe, and Mn, respectively, during the growing and gilt-developer phases. Reduced inorganic and reduced chelated treatments were supplemented during all phases with 5, 25, 25, and 10 mg/kg of Cu, Zn, Fe, and Mn, respectively. The reduced chelated treatment supplied 50% of the supplemental Cu, Zn, Fe, and Mn in the form of metal proteinates, with the remainder from sulfate forms. Performance by control pigs did not differ from pigs fed the reduced trace mineral treatments during the nursery and grower-development periods. Gain:feed was lower (P < 0.05) for pigs fed the reduced inorganic compared with those fed the reduced chelated treatment during the nursery period. Trace mineral source did not affect performance during the growing or gilt-developer phase. Plasma Zn concentration and alkaline phosphatase activity were higher (P < 0.01) in control pigs than in those receiving reduced trace minerals during the nursery and growing phases. Plasma Cu concentration and ceruloplasmin activity were generally not affected by treatment. Hemoglobin concentrations were lower (P < 0.05) for the reduced inorganic compared with the reduced chelated treatment in the nursery phase. Fecal concentrations of Cu, Zn, and Mn were lower (P < 0.05) in pigs fed reduced trace minerals than in controls during all production phases. Fecal Zn concentration during the nursery and fecal Cu concentrations during the growing and gilt-developer phases were lower (P < 0.05) in pigs fed the reduced chelated compared with the reduced inorganic treatment. Results indicate that reducing the concentrations of Zn, Cu, Mn, and Fe typically supplemented to pig diets will greatly decrease fecal mineral excretion without negatively affecting pig performance from weaning through development.}, number={7}, journal={Journal of Animal Science}, author={Creech, B. L. and Spears, J. W. and Flowers, W. L. and Hill, G. M. and Lloyd, K. E. and Armstrong, T. A. and Engle, T. E.}, year={2004}, pages={2140–2147} }
 @article{engle_spears_2004, title={Effect of finishing system (feedlot or pasture), high-oil maize, and copper on conjugated linoleic acid and other fatty acids in muscle of finishing steers}, volume={78}, number={2}, journal={Animal Science (Penicuik, Scotland)}, author={Engle, T. E. and Spears, J.W.}, year={2004}, pages={261–269} }
 @article{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{engle_fellner_spears_2001, title={Copper status, serum cholesterol, and milk fatty acid profile in Holstein cows fed varying concentrations of copper}, volume={84}, ISSN={["1525-3198"]}, DOI={10.3168/jds.S0022-0302(01)74678-4}, abstractNote={An experiment was conducted to determine the effects of dietary copper (Cu) on Cu status and lipid metabolism in Holstein cows. Three primiparous and 21 multiparous Holstein cows were utilized in this experiment. Groups of three cows similar in parity, days in milk, and milk yield were assigned randomly to one of the following three treatments: 1) control (no supplemental Cu), 2) 10 mg of Cu/kg of DM from Cu sulfate (CuSO4), and 3) 40 mg of Cu/kg of DM from CuSO4. Liver Cu concentrations were higher in Cu supplemented cows at the end of the 61-d study. Cows receiving 40 mg of Cu/kg of DM had higher liver Cu concentrations than cows receiving 10 mg of Cu. Plasma Cu concentrations were similar across treatments. Total serum cholesterol concentrations were higher in cows receiving supplemental Cu. Cows receiving 40 mg of Cu/kg of DM had higher serum cholesterol concentrations than cows receiving 10 mg of Cu. Dry matter intake, average daily milk production, and milk lipid, protein, and somatic cell numbers were similar across treatments. On d 61, milk fatty acids C18:1 trans and C18-conjugated dienes were lower in cows receiving supplemental Cu relative to the nonsupplemented controls. Cows receiving 40 mg of Cu/kg of DM had higher C12:0 and lower C18:2 and total polyunsaturated fatty acids in milk than cows receiving 10 mg of Cu/kg of DM. These results indicate that Cu supplementation alters lipid metabolism in high producing dairy cows and that Cu supplementation at 40 mg/kg of DM for 61 d can elevate liver Cu concentrations to levels considered to be marginally toxic in dairy cattle.}, number={10}, journal={JOURNAL OF DAIRY SCIENCE}, author={Engle, TE and Fellner, V and Spears, JW}, year={2001}, month={Oct}, pages={2308–2313} }
 @article{armstrong_spears_engle_see_2001, title={Effect of pharmacological concentrations of dietary copper on lipid and cholesterol metabolism in pigs}, volume={21}, ISSN={["0271-5317"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0034754358&partnerID=MN8TOARS}, DOI={10.1016/s0271-5317(01)00332-3}, abstractNote={Abstract An experiment was conducted to determine if pharmacological concentrations of copper (Cu) affect lipid and cholesterol metabolism in Cu-adequate pigs. Treatments consisted of: control (10 ppm Cu as cupric sulfate, CuSO 4 ); control + 66 or 225 ppm Cu as CuSO 4; control + 33, 66, or 100 ppm Cu as cupric citrate (CuCit). Pigs were fed their respective diets throughout the nursery (35 d) and growing-finishing (GF; 103 d) phases. Copper increased (P 4 relative to the control on d 42 of the GF phase. Percent lipid and cholesterol concentrations of the semitendinosus muscle were not affected by Cu. Lipid percentage of the longissimus muscle was decreased (P 4 compared to the control, but Cu did not affect cholesterol concentration or fatty acid profile. These results indicate that pharmacological concentrations of Cu have little effect on cholesterol and lipid metabolism in the Cu-adequate pig.}, number={9}, journal={NUTRITION RESEARCH}, author={Armstrong, TA and Spears, JW and Engle, TE and See, MT}, year={2001}, month={Sep}, pages={1299–1308} }
 @article{engle_spears_2001, title={Performance, carcass characteristics, and lipid metabolism in growing and finishing Simmental steers fed varying concentrations of copper}, volume={79}, DOI={10.2527/2001.79112920x}, abstractNote={An experiment was conducted to determine the effects of dietary copper (Cu) on performance, carcass characteristics, and lipid metabolism in Simmental steers. Thirty-six Simmental steers (329.3 +/-11.4 kg) were stratified by weight and randomly assigned to treatments. Treatments consisted of the following: control (no supplemental Cu) and 10 or 40 mg Cu/kg DM from Cu sulfate. Each treatment consisted of six replicate pens, with each pen containing two steers. A corn silage-soybean meal-based diet was fed for 56 d. Steers were then switched to a high concentrate diet. Performance was not affected by treatment during the growing or finishing phases. Plasma Cu concentrations were higher (P < 0.05) in steers receiving supplemental Cu by d 56 of the growing phase and remained higher (P < 0.05) at all 28-d sampling periods during the finishing phase. Liver Cu concentrations were higher (P < 0.001) in steers receiving supplemental Cu at the end of the growing phase and on d 84 and at the end of the finishing phase. Steers supplemented with 40 mg Cu had higher (P < 0.001) liver Cu concentrations than those supplemented with 10 mg Cu/kg DM. Serum and longissimus muscle cholesterol concentrations were similar between treatments. Longissimus muscle and backfat fatty acid composition was similar between treatments. These results indicate that Cu supplementation given to Simmental steers increased Cu status but had no effect on performance, carcass characteristics, or lipid or cholesterol metabolism.}, number={11}, journal={Journal of Animal Science}, author={Engle, T. E. and Spears, J. W.}, year={2001}, pages={2920–2925} }
 @article{engle_spears_l._edens_2000, title={Dietary copper effects on lipid metabolism and circulating catecholamine concentrations in finishing steers}, volume={78}, DOI={10.2527/2000.78102737x}, abstractNote={Forty-eight Angus and Hereford x Angus steers were used to determine the effects of copper (Cu) on lipid and catecholamine metabolism. Steers were stratified by weight within breed and randomly assigned to treatments. Treatments consisted of 0 (control, no supplemental Cu), 10, or 40 mg of supplemental Cu (from Cu2(OH)3Cl)/kg DM. Steers were fed a corn silage-soybean meal-based growing diet for 42 d. Animals were then switched to a high-concentrate finishing diet and remained on the same dietary treatments. On d 70, indwelling jugular catheters were nonsurgically inserted into five steers per treatment. Blood samples were obtained from steers after a 24-h period of feed withdrawal, 1 h after feeding, and after i.v. administration of norepinephrine and were subsequently analyzed for nonesterified fatty acid (NEFA) and catecholamine concentrations. Average daily gain over the finishing period was higher (P < 0.06) in steers receiving supplemental Cu. Serum total cholesterol concentrations were reduced (P < 0.05) on d 84 and 112 in steers supplemented with Cu. Serum norepinephrine (P < 0.14) and NEFA concentrations following feed withdrawal tended (P < 0.12) to be higher in Cu-supplemented steers. Postfeeding norepinephrine concentrations tended to be higher (P < 0.14) in Cu-supplemented steers. Nonesterifled fatty acid concentrations were lower (P < 0.10) in Cu-supplemented steers after norepinephrine administration. Backfat depth was decreased (P < 0.10) and longissimus muscle polyunsaturated fatty acid percentages were increased (P < 0.10) in steers receiving supplemental Cu. These results indicate that Cu addition to a finishing diet containing 5 mg Cu/kg DM alters lipid metabolism. The reduction in backfat depth may be due to copper altering catecholamine metabolism in steers.}, number={10}, journal={Journal of Animal Science}, author={Engle, T. E. and Spears, J. W. and L. and Edens, F. W.}, year={2000}, pages={2737–2744} }
 @article{engel_spears_2000, title={Dietary copper effects on lipid metabolism, performance, and ruminal fermentation in finishing steers}, volume={78}, DOI={10.2527/2000.7892452x}, abstractNote={Sixty Angus steers (391.1+/-6.1 kg) were used to determine the effects of dietary Cu concentration on lipid metabolism and ruminal fermentation. Steers were stratified by weight and randomly assigned to treatments. Treatments consisted of 0 (control), 10, or 20 mg of supplemental Cu (as CuSO4)/kg diet DM. Steers were housed in pens equipped with individual electronic Calan gate feeders. On d 86 and 92, ruminal fluid was collected from two steers/treatment for IVDMD determination. Equal numbers of steers per treatment were slaughtered after receiving the finishing diets for 96 or 112 d. Gain, feed intake, feed efficiency, IVDMD, and ruminal VFA molar proportions were not affected by Cu supplementation. Copper supplementation increased (P < .05) liver Cu concentrations, and steers supplemented with 20 mg Cu/kg DM had higher (P < .05) liver Cu concentrations than steers supplemented with 10 mg Cu/kg DM. Serum total cholesterol concentrations were reduced by d 56 and at subsequent sampling dates in steers receiving supplemental Cu. Longissimus muscle cholesterol concentrations were lower (P < .10) in steers supplemented with Cu. Backfat depth was less (P < .05) in steers receiving supplemental Cu, but marbling scores were similar across treatments. Unsaturated fatty acid composition of longissimus muscle was increased (P < .05) and saturated fatty acid composition tended (P < .12) to be reduced in Cu-supplemented steers. Polyunsaturated fatty acid concentrations were higher (P < .05) in steers receiving Cu. These results indicate that addition of 10 or 20 mg Cu/kg to a high-concentrate diet containing 4.9 mg Cu/kg DM alters lipid and cholesterol metabolism in steers but does not affect ruminal fermentation.}, number={9}, journal={Journal of Animal Science}, author={Engel, T. E. and Spears, J. W.}, year={2000}, pages={2452–2458} }
 @article{armstrong_spears_heugten_engle_wright_2000, title={Effect of copper source (cupric citrate vs cupric sulfate) and level on growth performance and copper metabolism in pigs}, volume={13}, ISSN={["1011-2367"]}, DOI={10.5713/ajas.2000.1154}, number={8}, journal={ASIAN-AUSTRALASIAN JOURNAL OF ANIMAL SCIENCES}, author={Armstrong, TA and Spears, JW and Heugten, E and Engle, TE and Wright, CL}, year={2000}, month={Aug}, pages={1154–1161} }
 @article{engle_spears_2000, title={Effects of dietary copper concentration and source on performance and copper status of growing and finishing steers}, volume={78}, number={9}, journal={Journal of Animal Science}, author={Engle, T. E. and Spears, J. W.}, year={2000}, pages={2446–2451} }
 @article{engle_spears_armstrong_wright_odle_2000, title={Effects of dietary copper source and concentration on carcass characteristics and lipid and cholesterol metabolism in growing and finishing steers}, volume={78}, DOI={10.2527/2000.7841053x}, abstractNote={We conducted an experiment to determine the effects of dietary copper (Cu) source and level on carcass characteristics, longissimus muscle fatty acid composition, and serum and muscle cholesterol concentrations in steers. Sixty Angus and Angus x Hereford steers were stratified by weight and initial liver Cu concentration within a breed and randomly assigned to treatments. Treatments consisted of: 1) control (no supplemental Cu); 2) 20 mg Cu/kg DM from Cu sulfate (CuSO4); 3) 40 mg Cu/kg DM from CuSO4; 4) 20 mg Cu/kg DM from Cu citrate; 5) 20 mg Cu/kg DM from Cu proteinate; and 6) 20 mg Cu/kg DM from tribasic Cu chloride. A corn silage-soybean meal-based diet was fed for 56 d. Steers were then switched to a high-concentrate diet. Equal numbers (n = 5) of steers per treatment were slaughtered after receiving the finishing diets for either 101 or 121 d. Serum cholesterol was not affected by treatment during the growing phase but was decreased (P < .05) in steers supplemented with Cu by d 84 of the finishing period and remained lower (P < . 05) at subsequent sampling periods. Longissimus muscle cholesterol concentration tended to be reduced (P < .11) by Cu supplementation. Hot carcass weight and backfat were lower (P < .05) in animals receiving supplemental Cu. However, Cu-supplemented and control steers had similar marbling scores. Longissimus muscle polyunsaturated fatty acid concentrations (18:2 and 18:3) were increased (P < .07) and saturated fatty acid concentrations tended (P < . 11) to be reduced by Cu supplementation. These results indicate that as little as 20 mg of supplemental Cu/kg diet can reduce backfat and serum cholesterol and increase muscle polyunsaturated fatty acids in steers fed high-concentrate diets.}, number={4}, journal={Journal of Animal Science}, author={Engle, T. E. and Spears, J. W. and Armstrong, T. A. and Wright, C. L. and Odle, J.}, year={2000}, pages={1053–1059} }
 @article{engle_spears_fellner_odle_2000, title={Effects of soybean oil and dietary copper on ruminal and tissue lipid metabolism in finishing steers}, volume={78}, DOI={10.2527/2000.78102713x}, abstractNote={An experiment was conducted to determine the effects of Cu and soybean oil (SBO) supplementation on ruminal and tissue lipid metabolism and carcass characteristics in finishing steers. Sixty Angus steers (369.0 +/- 10.1 kg) were stratified by weight and randomly assigned to treatments in a 2 x 2 factorial arrangement, with factors being 0 or 20 mg of supplemental Cu/kg DM from Cu sulfate and 0 or 4% SBO. Steers were fed a high-concentrate basal diet that contained 5.3 mg Cu/kg DM. Average daily gain and feed intake were reduced (P < 0.01) by SBO but were not affected by Cu. Gain:feed ratio was not affected by treatment. Liver Cu concentrations were higher (P < 0.01) in steers receiving supplemental Cu and lower (P < 0.04) in SBO-supplemented steers. Copper supplementation tended to reduce (P < 0.12) and SBO supplementation tended to increase (P < 0.11) serum cholesterol concentrations. Backfat depth was reduced (P < 0.10) by Cu and SBO supplementation. Marbling scores and longissimus muscle lipid content were not affected by Cu supplementation; however, SBO supplementation reduced (P < 0.01) marbling scores. Longissimus muscle polyunsaturated fatty acids tended to be increased (P < 0.14) in Cu-supplemented steers. Longissimus muscle C18-conjugated dienes and the 18:1 trans isomer were increased (P < 0.05) in SBO-supplemented steers. Ruminal fluid 18:3 was increased (P < 0.05) and the 18:1 trans isomer was decreased (P < 0.05) in Cu-supplemented steers. These results indicate that as little as 20 mg of supplemental Cu/kg DM can reduce backfat and may alter lipid metabolism in steers fed high-concentrate diets.}, number={10}, journal={Journal of Animal Science}, author={Engle, T. E. and Spears, J. W. and Fellner, Vivek and Odle, Jack}, year={2000}, pages={2713–2721} }
 @article{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} }
 @article{engle_nockels_kimberling_weaber_johnson_1997, title={Zinc repletion with organic or inorganic forms of zinc and protein turnover in marginally zinc-deficient calves}, volume={75}, DOI={10.2527/1997.75113074x}, abstractNote={We conducted two experiments using marginally Zn-deficient (-Zn) calves to determine which supplemental chemical form of Zn would most rapidly reverse certain Zn deficiency signs and to determine whether a change in protein turnover had occurred in Zn deficiency. In Exp. 1, 40 crossbred beef heifers were allocated by BW to four groups. The control group received 23 mg Zn/kg diet DM from ZnSO4 supplemented to the -Zn diet (17 mg Zn/kg diet DM). The three other groups received the -Zn diet. After 21 d, based on a decreased (P < .05) feed efficiency, they were deemed -Zn. Cell-mediated immune (CMI) response to phytohemagglutinin (PHA) was reduced (P < .05) but plasma and liver Zn were unaffected in the -Zn calves. Zinc was repleted by feeding iso-Zn amounts (23 mg Zn/kg diet DM) from Zn lysine, Zn methionine, or ZnSO4. At 8 h after injection of PHA, control CMI response values were similar to Zn Methionine, and Zn lysine was lower (P < .05). In Exp. 2, 10 Holstein steers were allocated by BW to two groups. One group received the -Zn diet, and the other received the +Zn diet. Urine collections were obtained from both groups of calves when the -Zn calves showed a decrease (P < .05) in feed efficiency relative to the controls and when they were repleted with 23 mg Zn/kg diet DM from ZnSO4 and their feed efficiency had returned to that of the controls. Urinary 3-methylhistidine indicated that -Zn calves had less (P < .05) daily protein degradation than the controls. Refeeding Zn to the -Zn group did not change BW or daily protein degradation. Results indicated that a marginal Zn deficiency decreased fractional accretion rate, increased (P < .05) urine excretion, and tended to increase (P < .19) Na and decrease (P < .12) K concentrations in the urine.}, number={11}, journal={Journal of Animal Science}, author={Engle, T. E. and Nockels, C. F. and Kimberling, C. V. and Weaber, D. L. and Johnson, A. B.}, year={1997}, pages={3074–3081} }