Properties of the Colostrum of the Dairy Cow. IV. Effect of Form of Vitamin A and of Tocopherol Supplements on Concentrations of Vitamin A and Carotenoids

Abstract

Summary The rations of dairy cows and heifers were supplemented with either various amounts of tocopherols or with large quantities of vitamin A ester, vitamin A alcohol or vitamin A alcohol plus tocopherols during the terminal 4 weeks (average minimum) of gestation. The relative effects of these prepartal supplements on vitamin A and carotenoid concentrations of colostrum and early milk were investigated. In view of the individual variation observed within the same groups, differences found in vitamin A concentrations in colostrum and early milk could not be ascribed to the form or combination of vitamin supplements given. Thus, vitamin A ester, vitamin A alcohol and vitamin A alcohol plus tocopherols appeared to be of a similar value in affecting increases in vitamin A levels of colostrum and early milk. In a trial with a limited number of cows, addition of tocopherols at various levels to barn rations did not increase substantially vitamin A content of colostrum and early milk. Neither the form of vitamin A supplement given nor the addition of tocopherols had a significant effect on carotenoid levels of the early mammary secretions.