分娩前後の乳牛のリポタンパク質中のコレステロール値とトリグリセリド値のプロファイル

Abstract

Lipoproteins are macromolecule complexes of protein, phospholipids, cholesterol, cholesterol esters, and triglycerides, and the lipoproteins transport cholesterol and triglycerides throughout the animal body. The objective of the present study was to investigate a profile of cholesterol and triglyceride concentrations in four lipoproteins during the peripartum period in Holstein dairy cows. Sixty nine blood samples for lipoprotein analysis were taken from 41 periparturient cows on 16 dairy farms. The analysis determined cholesterol and triglyceride concentrations in four lipoprotein fractions which included chylomicron (CM), very low density lipoprotein (VLDL), low density lipoprotein (LDL), and high density lipoprotein (HDL). Analysis of covariance compared cholesterol and triglyceride concentrations in four lipoprotein fractions between pre- and post-partum periods in cows. Correlation analysis was performed between cholesterol and triglyceride concentrations in the four lipoproteins. Means (±SEM) of total concentrations of cholesterol and triglyceride in pre-partum cows were 83.61 (±3.9) and 14.1 (±0.69) and mg/dl, respectively. After calving, the total concentrations of cholesterol and triglyceride decreased to 70.31 (±4.07) and 5.53 (±0.57) mg/dl, respectively. The highest HDL cholesterol concentration and the highest VLDL triglyceride concentration were found among the four lipoprotein fractions. Cholesterol concentrations in all the four fractions decreased from pre-partum to post-partum periods (P<0.05), whereas triglyceride concentrations in the two fractions of VLDL and CM decreased (P<0.05). Especially, VLDL cholesterol and VLDL triglyceride concentrations decreased by 70% or higher. In both pre-partum periods and post-partum periods, cholesterol concentrations were correlated between VLDL, LDL and HDL (P<0.05), but no such correlations were found for triglyceride concentrations. In conclusion, cholesterol and triglyceride concentrations in four fractions are differently related with the calving in dairy cows.