Incorporation of [1- 14C]acetate into the aliphatic δ-lactones of ruminant milk fat

Abstract

1. 1. Gas-liquid radiochromatography was employed to demonstrate that 14C from [1- 14C]acetate was incorporated in vivo into the aliphatic δ-lactones (δ-hydroxy fatty acids) of goat milk fat. 2. 2. The δ-C 10, δ-C 12, δ-C 14 and δ-C 16 lactones were isolated from milk fat samples collected at 5, 10, 15, 20 and 25 h following intravenous and intramammary administration of [1- 14C] acetate to two goats and the specific activities of the δ-lactones were determined. These values, in general, were of comparable magnitude to the specific activities of the saturated milk fatty acids of corresponding carbon chain lengths. 3. 3. Following intravenous administration of [1- 14C]acetate both the δ-lactones and the saturated fatty acids exhibited maximum specific activities at 5 h whereas following intramammary administration the δ-lactones and fatty acids exhibited maximum specific activities at 10 h. 4. 4. The results are consistent with the view that acetate is a common precursor of both the δ-lactones (δ-hydroxy fatty acids) and the saturated fatty acids and imply that the (δ-hydroxy fatty acids are produced from acetate in a manner similar to biosynthesis of the corresponding fatty acids rather than as products of long chain fatty acid oxidation.