The Minimum Vitamin A and Carotene Requirement of Cattle, Sheep and Swine

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Abstract
The results of experiments on the minimum vitamin A and carotene requirement of cattle, sheep and swine are reported. The night blindness test, supplemented by a check on storage either by depletion or by the antimony trichloride test on extracts of the liver tissue, was used as the criterion of sufficiency. Evidence was presented that the amount of vitamin A or carotene daily that just prevents night blindness, represents a physiological minimum. Carotene was furnished by alfalfa and by crystalline carotene dissolved in cottonseed oil. Vitamin A was supplied by cod liver oil. It was analyzed with a Hilger-Vitameter A and also by the antimony trichloride method and the results compared with similar analysis of U. S. P. reference cod liver oil. Limitations of expressing vitamin A in absolute terms are discussed. The minimum carotene requirement for all of the species studied was found to be 25 to 30 micrograms daily per kilogram body weight, an amount in agreement with similar data on the rat. The minimum vitamin A requirement on the basis of the analysis and criteria used was found to be 6 to 8 micrograms daily per kilogram body weight. These figures also appear to agree well with data on the rat calculated from present conversion factors for biological units. Excellent growth occurred at these levels yet storage after extended periods was meager. The data support the hypothesis proposed by Guilbert and Hart ('35) that vitamin A requirement is directly related to body weight rather than to energy requirement and that the requirement of other species of mammals may be predicted on this basis. Calculations from clinical data indicate that the human requirement cannot be far different from that of the species studied. Indications of poor use of carotene by puppies is cited as a possible limitation in applying the generalization for carotene to carnivores. Data on depletion periods for swine and sheep together with observations on reproduction are presented and discussed.

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