The metabolism of [U-¹⁴C]glucose, [1-¹⁴C]palmitic acid and [1-¹⁴C]stearic acid by the lactating mammary gland of the sow

Abstract

Summary (1) Lactating Large White sows were given an intravenous infusion of [U- 14 C]glucose (3 sows), or of triglycerides containing [1- 14 C]palmitic acid (1 sow) or [1- 14 C]stearic acid (1 sow). (2) The contribution of labelled plasma constituents to the synthesis of milk citrate, lactose, triglyceride glycerol, individual amino acids of the milk proteins and individual fatty acids of the triglyceride fraction was estimated by the ‘transfer quotient’ method. For the glucose infusions the mean values for the transfer quotients were: lactose, 70%; citrate, 42%; glyceride glycerol, 38%; protein, 3%; laurate, 6%; myristate, 12%; palmitate, 6%; palmitoleate, 4% and stearate, 2%. Palmitic acid of the plasma triglycerides made similar contributions of about 60% to the palmitic and palmitoleic acids of milk fat, whereas stearic acid made a major contribution (71 %) to the stearic acid of milk fat but a smaller contribution (42%) to oleic acid. (3) The results are compared with corresponding values for the goat and the cow.