Effect of Form of Alfalfa When Fed as the Sole Source of Roughage to Guernsey Cows on the Carotenoid and Vitamin A Content of Milk

Abstract

The effect of feeding artificially-dried and chopped, artificially-dried and pelleted, and field-cured and field-baled forms of alfalfa as the sole source of roughage on the carotenoid and vit. A content of the milk was studied,18 Guernsey cows being used in a double change-over design. During the feeding of the chopped form, the carotenoid and vit. A concn. of the milk and of the milk fat, and also total amts. of these constituents secreted, were found to be significantly greater than those for the field-baled and pelleted forms of the alfalfa. Although the carotenoid intake during the feeding of the pelleted forms was of approx. the same magnitude as that for the chopped form and more than 7 times greater than that for the field-baled form, the carotenoid and vit. A content of the milk was less than that observed for the chopped form and approx. the same as that for the field-baled. Apparent mammary transfer of the ingested carotenoids was least during the feeding of the pelleted form of alfalfa and greatest for the field-baled form. The estimated vit. A content of the butter as calculated from the carotenoid intakes during the feeding of each form of the alfalfa was approx. similar to the observed values for the chopped form, considerably lower for the pelleted form, and higher for the field-baled form.