The role of n-valeric acid in the synthesis of the higher saturated straight-chain acids containing an odd number of carbon atoms in bovine milk fat

Abstract

The distribution of C14 among fatty acids in the milk fat of a lactating cow, which had been injected with [carboxy-C14] valerate, showed that the saturated straight-chain acids of similar molecular weight, containing odd and even numbers of C atoms, had closely similar specific activities. Valeric acid is not, therefore, a direct precursor in the formation of saturated straight-chain acids of milk fat containing an odd number of C atoms. The present results are consistent with the degradation in vivo to acetate and propionate. The present results suggest that the volatile fatty acids up to and including C10 are synthesized predominantly in the udder, and that those from C12 to C18 are predominantly synthesized elsewhere. The high specific activity of gly-cerol C shows valerate to be glycogenic rather than lipogenic.