Origin of Glyceride Fatty Acids in Cow Milk Fat

Abstract

The pattern of the specific activities of milk fatty acids from a cow that had received a single injection of 1-14C -CH3 COONa agreed with that found by other workers and supported the current view that milk fatty acids up to myristic are synthesized from blood acetate and that palmitic and stearic acids are derived mainly from blood glycerides. On the other hand, following continuous infusion of l-14C-CH3COONa, the milk fatty acids, on the basis of specific activities were divisible into 3 groups-C2:0 to C10:0, C12:0 to C16:0 and C18:0, C18:l consistent with their formation from different routes. The eventual elevation of the specific activity of palmitic acid to that of the lower fatty acids indicates its synthesis from blood acetate albeit by a slower pathway. The origin of part of the stearic acid in milk from blood acetate was likewise indicated. The relatively high specific activity of oleic acid suggested that this may be synthesized from sources other than stearic acid.