Abstract
Twelve half-sib Hereford steers, equally randomized to four rations containing 0, 5, 10 and 15% added animal fat were utilized in isolating and studying the serum lipoproteins of the bovine. The four separate lipoprotein fractions observed were: chylomicrons, density 1; density 1.007 to 1.044; LDL2, density 1.044 to 1.063; and HDL, density 1.063 to 1.210 g/ml. The HDL comprized 76% of the total lipoprotein present while the LDL1 and LDL2 were 5.4 and 18.5%, respectively. The lipid content of the LDL was approximately 85% and the HDL was 41% lipid while the chylomicrons carried a very small portion of the total serum lipid. The individual lipoprotein fraction concentrations were not significantly influenced by diet. The fatty acid profiles of the phospholipid, triglyceride, free fatty acid and cholesterol ester lipid classes of chylomicron, LDL1, LDL2, total LDL, HDL and whole serum fraction of the serum within a particular diet and sampling period are presented. Within each of the lipid classes studied, the fatty acids of the chylomicrons were in most comparisons the only lipoprotein fraction which revealed large deviations from the whole serum profile and this was due primarily to a lower level of linoleic acid present in this fraction. The LDL1; LDL2, total LDL and HDL fractions were in general not significantly different in fatty acid composition from the whole serum or each other. The fatty acid levels of the lipid classes of the lipoprotein fractions were in general not influenced differently by diet from the whole serum fatty acid profile. Many significant (P<.05) changes due to the diets in the fatty acid levels within a lipoprotein or the whole serum fraction of a serum lipid fraction were observed. Most of these changes were nearly linear with the increased fat levels in the basic ration. However, the chylomicron fraction was somewhat different in that few significant (P<.05) dietary effects on the fatty acid composition of the lipid fractions occurred. Copyright © 1971. American Society of Animal Science . Copyright 1971 by American Society of Animal Science.