THE UPTAKE FROM THE BLOOD OF TRIGLYCERIDE FATTY ACIDS OF CHYLOMICRA AND LOW-DENSITY LIPOPROTEINS BY THE MAMMARY GLAND OF THE GOAT

Abstract

Although a portion of the fatty acids of milk triglycerides are known to be synthesized within the mammary gland, part are derived from unknown lipid fractions of the blood (Folley & McNaught, 1961). The experiments reported in the present paper were designed to discover which plasma-lipid fractions provide these fatty acids. It is shown that, in lactating goats, there is an arteriovenous difference across the mammary gland in the tri- glyceride fatty acids of chylomicra and low-density lipoproteins of density 1F005-l019 that could account for a large portion of the fatty acids of milk. No significant arteriovenous differences could be detected in the free fatty acids of plasma or in the fatty acids of the low-density lipoproteins of d 1-019-1063 or of high-density lipoproteins. Arteriovenous measurements are also reported for D-fi-hydroxybutyrate, acetoacetate and free glycerol. METHODS Blood 8ampling. Arterial and mammary venous blood samples were taken from four Saanen goats at the A.R.C. Institute of Animal Physiology (see Table The animals were being given a diet of hay ad libitum and a balanced cereal ration (plus vitamins A and D and minerals) similar to that commonly fed to milking cows and containing about 5% of fat. The cereal ration was given twice daily, when the