The Relationship of the Prepartum Diet to the Carotene and Vitamin A Content of Bovine Colostrum

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Abstract
A study has been made of the relationship of the prepartum diet to the vitamin A and carotene content of bovine colostrum. Four rations were fed to 29 Holstein and 4 Guernsey heifers during the last 60 days of their gestation periods. The rations were a low-carotene ration of wheat straw and a concentrate mixture; a. standard dry-cow ration of concentrate, mixed hay and corn silage; the standard ration supplemented with one million I.U. of carotene daily; and the standard ration supplemented with one million I.U. of vitamin A daily. Colostrum from cows receiving the low-carotene ration contained significantly less vitamin A per gram of butterfat than did colostrum from cows receiving the standard dry-cow ration. The carotene content per g. of butterfat in the colostrum from the carotene-supplemented cows was significantly higher than that from the other groups although the vitamin A content was not increased. Colostrum from cows receiving the vitamin A supplement contained an average of 687 mg. per 100 ml. or 164.5 mg. per g. of butterfat, while the colostrum from the standard dry-cow ration group contained only 374 mg. per 100 ml. or 91 mg. per g. of butterfat, showing that the vitamin A content of colostrum may be influenced by the prepartum diet. Regardless of the form of vitamin A in the ration, the ester form of vitamin A predominated in the colostrum. Highly significant positive correlations were found between the plasma carotene and vitamin A of the cows 18 days before calving and the carotene and vitamin A content of the colostrum.

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