Qualitative and quantitative alterations of bovine serum lipoproteins with ageing

Abstract 1. 1. Plasma lipoproteins from six calves at 8, 43 and 118 days old, six heifers and six cows were separated by density gradient ultracentrifugation. For each sample lipoproteins bands were visualized by prestained control and characterized by electrophoretic, chemical and morphological analysis. 2. 2. Two resolved bands were detected in the low density lipoprotein fraction (LDL). At an early stage of development, LDL I and LDL II were present with almost equal concentration. With ageing, LDL II became the major fraction of LDL lipoproteins. 3. 3. HDL were isolated as a single band distributed over the range 1.064–1.166 mg/ml in young calf and 1.050–1.152 mg/ml in adult. This progressive decrease of density limits with ageing, associated with a decrease of protein content and an increase of phospholipids and cholesteryl esters content, was consistent with higher HDL particle diameters in adult. 4. 4. With ageing, free cholesterol/esterified cholesterol ratio decreased in LDL fractions and increased in HDL fractions.