Studies on Ketosis in Dairy Cattle. X. The Effect of a Vitamin A Deficiency

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Abstract
Detailed observations were made on 13 cows which were maintained on a low carotene diet for approx. 4 months prepartum and 3 weeks postpartum. The vitamin A depletion of these cows was accentuated by the feeding of a concentrate ration containing 40% soybeans which was later shown to exert a marked depressing action on blood plasma and liver vitamin A. Five of the cows received a vitamin A supplement prepartum which resulted in the birth of 4 normal-appearing calves. The other 8 cows dropped calves which showed marked signs and/or symptoms of a vitamin A deficiency. The blood plasma vitamin A values of these 8 cows were extremely low during the postpartal period and 1 cow exhibited marked symptoms of a vitamin A deficiency. Of the 8 cows, 4 were maintained on a low level of energy intake for 3 weeks postpartum (50% of requirements). The 5 cows receiving the vitamin A supplement prepartum were on the same low level of energy intake postpartum. In spite of the severe vitamin A depletion and deficiency produced in these cows, none showed symptoms of ketosis and the degree of hypoglycemia produced by partial fasting was as large in the case of the vitamin A-supplemented cows as in the vitamin A-depleted cows. The cows exhibiting a marked vitamin A depletion but receiving higher levels of energy intake postpartum exhibited normal levels of glucose during the postpartal period. None of the cows showed symptoms of ketosis. It is concluded that not only is spontaneous ketosis, as it is observed under field conditions, not due to a vitamin A deficiency but that a vitamin A deficiency per se does not produce ketosis in dairy cows in the postpartal period.