Effects of Vitamin A and Carotene Intake on Depletion Time of Young Dairy Calves

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Abstract
The store of vit. A dairy calves have at 90 days of age was measured by placing the calves on a vit. A free ration and following the vit. A level in the blood plasma until it fell below 4 [mu]g. of vit. A per 100 ml. of blood plasma. The amt. of vitamin consumed by some of the calves was known. Expressing the total vit. A intake in terms of body wt., a good correlation was found between total intake per lb. of body wt. and the depletion time. To have depletion times comparable to calves which were allowed to suckle their dams, 50,000 I.U. of vit. A per day must be fed to 50 or more days of age. Supplementing the ration with 25,000 and 50,000 I.U. of vit. A had a beneficial effect. Among the supplemented calves fewer digestive disturbances were encountered and fewer calves died.