Metabolism of Fatty Acids by Adipose Tissue and Liver of Cows Fed Normal, Restricted Roughage or MgO Supplemented Rations

Abstract

Two Latin square experiments used 11 lactating cows to study dietary effects on fatty acid metabolism in serum, liver, and adipose tissue. Lipoprotein lipase and fatty acid esterifying activities from adipose tissue homogenates were increased and milk fat depressed when the ration was switched from normal to restricted-roughage, high-grain. Fatty acid esterification in liver was correlated (r = .89) with milk fat concentration but was not uniformly affected by ration. Mammary gland uptake of triglycerides from dextran sulfate precipitable lipoproteins and milk fat percentage was greater for cows fed MgO supplemented rations than for cows fed the other rations. The proportion of stearic acid decreased and C18:1 increased in the dextran sulfate precipitable lipoprotein triglycerides for cows fed restricted-roughage, high-grain rations compared to those fed other rations. Only stearic acid was selctively assimilated by the mammary gland. Cholesterol linoleate increased in the dextran sulfate precipitable lipoproteins when rations were switched from normal to restricted-roughage, high-grain. Changes in both serum lipids and tissue enzymes are associated with an increased flux of fatty acids toward adipose tissues during restricted-roughage, high-grain feeding. © 1972, American Dairy Science Association. All rights reserved.