Effects of Zinc Deficiency per se on Feed Efficiency, Serum Alkaline Phosphatase, Zinc in Skin, Behavior, Greying, and other Measurements in the Holstein Calf

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Abstract
Calves were fed a Zn-deficient diet until 21 wk old. To separate effects of Zn deficiency per se from the indirect influence of reduced feed intake, groups of calves were fed the control diet both ad libitum and in amounts restricted to somewhat less than those voluntarily consumed by the deficient ones. Zinc deficiency per se resulted in lower feed efficiency, reduced serum alkaline phosphatase, and lower blood hemoglobin, but did not significantly affect serum lactic dehydrogenase or packed cell volume. Likewise, in skin biopsy samples, zinc magnesium, dry matter percentage, and dry weight/unit area were unaffected. Attempts to determine the effect of the deficiency on respiration rate were unsuccessful because the deficient calves refused to respond to a variety of stimuli intended to cause vigorous exercise. The deficiency effects were reversible. Except for reduced weight gains, calves fed the control diet in limited amounts had no symptoms of a Zn deficiency. Several months after they had recovered, most of the formerly Zn-deficient calves, but none of the controls, had gray hair on spots from which skin samples had been surgically removed during the treatment period.