Utilization of acetate for milk-fat synthesis in the lactating goat

Abstract

The oxidation of acetate and its utilization for the synthesis of milk fatty acids in a lactating goat was investigated with the aid of (carboxy-C14) acetate. The half-life of body acetate in the lactating goat is not more than 50 min. Acetate is rapidly utilized for the synthesis of milk fatty acids; the specific activity:time curves of these, after the max. had been attained 3-4 hr. after the injn., decayed with a half-life of about 4 hrs. The plasma fatty acids contained much less C14 than the milk fatty acids and could not have been directly an important source of the latter. The steam-volatile fatty acids had a higher specific activity than the long-chain non-volatile acids indicating their independent synthesis. The hypothesis that the volatile fatty acids of milk originate from the degradation of long-chain acids (particularly of oleic) could not be confirmed. They may represent intermediates in the formation of long-chain acids. Milk cholesterol is synthesized in the udder and not derived from blood cholesterol.