Effect of isolation temperature on the determination of bovine plasma very low density lipoprotein concentrations

A split-plot design was used to determine effect of temperature on isolation of plasma very low density lipoproteins that were high in either saturated or polyunsaturated fatty acids. Four steers received abomasal infusion of 400 ml of water (control) or of corn oil, which served as the whole plot treatment, and the isolation of lipoproteins by ultra-centrifugation at 4, 20 and 37 degrees C were the subplot treatments. Measured concentrations of plasma very low density lipoproteins (less than 1.007 g/ml) in control steers was 59 and 19% of that at 37 degrees C when isolation occurred at 20 and 4 degrees C, respectively. Measured concentrations of lipoproteins with densities less than 1.024 g/ml were not affected by lowering the isolation temperature from 37 to 20 degrees C but were decreased approximately 50% at 4 degrees C. Abomasal infusion of corn oil for 48 h reduced plasma very low density lipoprotein concentration from 18.3 to 5.2 mg/dl (37 degrees C isolation). Triglycerides of lipoproteins isolated from animals during the abomasal corn oil infusion had less C18:2 (average 36.3 vs. 4.0%) fatty acids than during the control treatment. Reducing the temperature of isolation did not affect measured lipoprotein concentration in plasma obtained from animals during oil infusion. Reduction in isolation temperature has a greater effect on the recovery of very low density lipoproteins, which are relatively high in saturated fatty acids compared with those high in polyunsaturated fatty acids.