617. Variations in the carotene and vitamin A contents of herd butterfats throughout lactation

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Abstract
The carotene and vitamin A contents of the butterfat from the milk yielded by the cow in early lactation may be higher than normal for a period of up to 10 or 12 days after parturition.Seasonal changes in carotene content of butterfat from small herds of cows were governed almost entirely by the availability of carotene in the pasture and not by lactational influences.Seasonal changes in vitamin A content of the herd butterfats were relatively small during most or all of the lactational period. In certain years an increase in the vitamin A content during the autumn months was probably due to seasonal conditions and not to a lactational effect.