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Marginal zinc deficiency affects biochemical and physiological parameters in beef heifer calves |
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T. E. Engle, C. F. Nockels, K. L. Hossner, C. V. Kimberling, R. E. Toombs, R. S. Yemm, D. L. Weaber, A. B. Johnson |
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| Abstract |
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A study determined whether certain biochemical and physiological variables were altered during marginal Zn deficiency. Ten weaned crossbred Hereford Angus heifer calves, weighing 163 2 kg, were utilized. Five calves were fed a Zn-deficient (-Zn) brome-alfalfa hay diet containing 17 mg Zn/kg diet DM, and five calves were fed a Zn-adequate (+Zn) diet with 23 mg Zn/kg diet DM from ZnSO4 added to the -Zn diet (total diet, 40 mg Zn/kg diet DM), for 32 d. At 21 d the -Zn calves gad a reduction (p < .05) in feed efficiency. By 25 d, plasma Zn and alkaline phosphatase concentrations were reduced (p < .05) in the -Zn calves. Blood urea nitrogen, glucose, insulin, IGF-I, Cu plasma concent-ration and Zn and Cu concentrations of red blood cell (RBC) and liver were not altered (p > .05) by the -Zn diet through 25 d. In response to a single i. m. infection of dexamethasone (20 mg) on d 25, calves fed the two dietary Zn amounts showed no changes (p > .05) in plasma or RBC Zn and Cu concentrations, serum IGF-I, insulin, and glucose when measured at 6, 12, 24, 48, 72, and 96 h after injection. In response to an intradermal injection of phytohemagglutinin on d 30, cell mediated immune (CMI) response was reduced (p < .05) in the -Zn calves. These observations indicate that during a marginal Zn deficiency in calves, there was a decrease in feed efficiency, plasma Zn, serum alkaline phosphatase, and CMI response. |
| Keywords:
Zinc; Cattle; Feed Efficiency; Immune Response; Insulin-Like Growth Factor I; Dexamethasone |
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