The Effect of Feeding Menhaden (Fish) Oil on the Secretion of Milk and the Composition of Butter Fat in the Dairy Cow

The problem of the effect of diet on the quality and quantity of milk from the dairy cow has been one of great interest and the subject of numerous investigations, including those of Wing (1), Anderson (2), Eckles and Palmer (3), Mattick (4), Petersen (5), Maynard and MaCay (6) and Petersen, Palmer and Eckles (7).Milk as a glandular secretion and as a food is unique not only because it contains at least two biologically complete proteins, casein and lactalbumin, and a characteristic sugar, lactose, but also because it contains a fat that is composed of glycerides of oleic acid and of the entire series of saturated fatty acids up to stearic.Few of these compounds are ordinarily found in the food of the cow.Casein, lactalbumin, lactose and the lower fatty acids are apparently, therefore, products of the synthetic action of the mammary gland.The higher fatty acids, palmitic, stearie and oleic, appear to be derived for the most part from the blood lipids and hence from the fat of the diet.In a continuance of a series of investigations on the fate of highly unsaturated fatty acids in animal metabolism (8), the primary object of the present investigation was to trace definitely the passage of the characteristic highly unsaturated fatty acids of menhaden (fish) oil from the food into butter fat in the dairy cow.These acids consist of a mixture of the following (9) : Hexadecatrienoic ..........