Relative Value of Carotene from Alfalfa and Vitamin A from a Dry Carrier Fed to Lambs and Pigs1

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Abstract
Graded levels, 40, 80, 160 and 320 mcg. of carotene from artificially dehydrated alfalfa leaf meal or, 8, 16, 24 and 32 mcg. of vitamin A from a dry carrier per lb. of live weight per day were added to vitamin A depletion rations of 24 lambs and 32 pigs, partially depleted of their vitamin A stores, for a period of 6 weeks duration. Daily gains were not affected. Plasma vitamin A concentrations increased at diminishing rates and liver vitamin A concentrations increased at essentially constant rates with increasing intakes of carotene or vitamin A. Liver vitamin A was transformed to logarithms to minimize variances and along with plasma vitamin A resulted in essentially linear regressions on logarithms of intake. A greater rate of response with increasing vitamin A intake than with increasing carotene intake was observed. The relative values of carotene to vitamin A were determined from these linear regressions. Based on plasma vitamin A, the following carotene to vitamin A (alcohol) ratios on a weight basis were found: At the 40 mcg. carotene intake level, for the lambs 8:1 and for the pigs 6:1; at 80 mcg., respectively, 9:1 and 7:1; at 160 mcg., 11:1 and 9:1; and at 320 mcg., 13:1 and 11:1. Similar values based on log liver vitamin A were: At the 40 mcg. carotene intake level, 6:1 and 4:1; at 80 mcg., 8:1 and 5:1; at 160 mcg., 10:1 and 7:1; and at 320 mcg., 13:1 and 9:1. Copyright © . .