THE LIPID COMPOSITION OF ERYTHROCYTE MEMBRANES AND PLASMA LIPOPROTEINS IN "DOUBLE-MUSCLED" CATTLE

Abstract

The lipid composition of erythrocyte membranes was determined in 11 phenotypically extreme- and 11 normal-muscled cattle of a "double-muscled" (DM) breed group. The relative concentrations of lipid classes in erythrocyte membranes from extreme- and normal-muscled DM cattle were similar. Significant differences were observed in the relative concentrations of individual fatty acids in the erythrocyte membrane sphingomyelin and phosphatidylethanolamine fractions from extreme-compared with normal-muscled DM cattle. The most notable differences were a higher (P < 0.05) concentration of palmitic acid and a lower (P < 0.01) concentration of oleic acid in sphingomyelin from extreme-muscled DM cattle. In a second study, the total lipid composition of plasma, plasma high density lipoprotein (HDL) and plasma low plus very low density lipoprotein (LDL-VLDL) fractions was determined in six extreme- and six normal-muscled DM cattle. Extreme-muscled DM cattle had a lower (P < 0.05) concentrations of triacylglycerols in all three total lipid fractions and higher (P < 0.05) concentrations of cholesterol in plasma and cholesterol esters in the LDL-VLDL total lipid fraction as compared with normal-muscled DM cattle. The concentration of lysophosphatidylcholine was higher (P < 0.05) in the LDL-VLDL total lipid fraction from extreme-muscled DM cattle, but no other differences in the relative amounts of the phospholipids were observed. Extreme-muscled DM cattle had higher (P < 0.05) concentrations of polyunsaturated fatty acids in the plasma and LDL-VLDL total lipid fractions, with a similar trend occurring in the HDL total lipid fraction. The results of the first study demonstrate a change in fatty acid composition of the membrane, while those of the second indicate an increased rate of VLDL metabolism and/or lower rates of adipose fatty acid turnover in extreme- compared with normal-muscled DM cattle. Key words: Lipid composition, lipoproteins, double muscled cattle