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Influence of Breed and Ration on the Carotene and Vitamin A Content of Milk¹

University of Wisconsin

Abstract

Vitamin A activity in butter is due to the presence of two different chemical entities, viz. carotene and vitamin A. The variations in the yellow pigment of butter fat (carotene) in different breeds of dairy cattle have been observed for many years but studies on breed variations in the carotene-vitamin A output of dairy cattle are fragmentary. The fact that butter shows seasonal variations in its content of both carotene and vitamin A, paralleling the consumption of carotene containing feed, appears to be well established. However, the effect of various roughages on the increase in both of these components has not been clearly established. In view of the aforementioned uncertainties our studies present determinations of the carotene and vitamin A content of butter from individual cows of various breeds on known diets and of known nutritional history.

EXPERIMENTAL

In order to determine individual and breed variations under the same environmental and feeding conditions, butter fat samples were prepared from milk of individual cows from the university herd.

¹ Credit is due H. Steenbock, C. A. Baumann, G. Bohstedt and I. W. Rupel for their helpful suggestions. Part of this work has been published in detail in J. Biol. Chem. 105; 167, 1934.