Plasma lipoprotein profile in fasted and refed chickens of two strains selected for high or low adiposity

The plasma lipoprotein profile has been determined in fasted and refed 5-week-old male broilers selected for low or high adiposity. Lipoprotein classes were subfractionated by density gradient ultracentrifugation, appearing as distinct bands with the following densities: very low density lipoprotein (VLDL), d less than 1.013 g/ml; low density lipoprotein (LDL), d 1.023-1.046 g/ml and high density lipoprotein (HDL), d 1.052-1.130 g/ml; the physiochemical characteristics (chemical composition, electrophoretic mobility and particle size) of these particles were then assessed. HDL, seen as a single band, represented 80% of total lipoproteins, with VLDL and LDL accounting for 1% and 16%, respectively, in fasted birds. Lipoprotein profiles were similar in fasted and refed animals of both lines, with the exception that VLDL levels were some 14-fold and 7-fold higher in the lean and fat lines, respectively, in the refed state. The VLDL of fasted birds of both lines were enriched in protein and relatively homogeneous in size; by contrast, VLDL in the refed state contained more triglyceride and less cholesteryl ester and protein and were larger and more heterogeneous, possibly representing a mixture of portomicrons and VLDL of hepatic origin. Birds of the fat line in both nutritional states differed from lean birds in exhibiting elevated plasma lipid and lipoprotein [VLDL, intermediate density lipoprotein (IDL) and HDL] levels, evidence that liver activity is directed toward increased lipoprotein production and secretion in that line.