Utilization of Intravenously-Administered Carotene by Sheep and Cattle

Abstract

Eight fine-wool wethers and seven Hereford calves were given single intravenous injections of a solublized, aqueous carotene preparation. Blood samples were collected at intervals and analyzed for carotene and vitamin A. In wethers, increases in plasma vitamin A after carotene injections were highly significant, the mean values at 3, 6, 9, and 12 hours after injection being approximately twice the initial value. Blood carotene, after an initial rise, fell rapidly during the first 6 hours following injection, then declined slowly for the remaining 10 days. The effect on liver stores was questionable. In calves, carotene injection caused no significant differences in plasma vitamin A values. Plasma carotene remained quite constant near 85 meg. per 100 ml. for 2 to 24 hours following injection, then decreased slowly. No liver storage of vitamin A or carotene was evident from the comparison of liver samples taken 1 month before and 3 days after injection. Advanced vitamin A deficiency symptoms present in some of the calves were not relieved and appeared to progress during the 10 days of the experiment. The data obtained in these experiments indicate a wide difference between cattle and sheep in their ability to convert intravenously injected carotene to vitamin A. Copyright © . .