The Effect of Supplemental Vitamin A upon Growth, Blood Plasma Carotene, Vitamin A, Inorganic Calcium, and Phosphorus of Holstein Heifers

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Abstract
Feeding an avg. of 40,400 USP units of supplemental vitamin A per day to Holstein heifers receiving a normal ration resulted in no increase in rate of growth. Increasing the vitamin A supplement to an avg. of 129,400 USP units per day in addition to the 114,000 USP units supplied daily in the basal ration resulted in a significant increase in body wt. gains in Holstein heifers. Feeding supplemental vitamin A significantly increased the blood plasma vitamin A concns. and decreased the blood plasma carotene concns. of Holstein heifers. Blood plasma inorganic Ca and P concns. were not altered by feeding supplemental vitamin A.