Interrelationships between Carotene from Artificially Dehydrated Alfalfa and Vitamin A from a Dry Carrier When Fed Simultaneously to Holstein Calves

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Abstract
With the synthesis and commercial production of crystalline vitamin A and its incorporation into a dry carrier, its use by commercial feed manu- facturers has greatly increased. However, there is a lack of information on the interrelationships between carotene and vitamin A per se when fed simultaneously. Forty-eight 1-day-old male Holstein calves were used as test animals. Blood samples taken weekly from the 35th to the 175th day of age were analyzed for plasma vitamin A and carotenoid content. At the time of slaughter the liver of each test animal was analyzed for vitamin A and carotenoid content. The practical significance of the study is the finding that both sources of vitamin A may be included simultaneously in a ration without adverse effects. Editor. With the elucidation of the chemical structure of carotene and vitamin A, their interrelationshi ps have become more readily understood. There have, how- ever, been several reports which indicated that tile relationship is not as simple as the chemical structures might indicate. Using primarily plasma carotenoids and vitamin A as criteria, several workers have investigated the effect of massive doses of either compound when fed with the other to dairy animals. Large doses of vitamin A have been reported to suppress plasma carotenoid levels both in the calf ((7, 10, 15, 18) and in older animals (3, 8, 16, 21, 23). A similar sup- pression of the earotenoids in milk following large doses of vitamin A to milking animals has been observed (3, 9, 11, li). In none of these studies was the intake

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