SALVANTE, K.G.*; WALLOWITZ, M.; WALZEM, R.L.; WILLIAMS, T.D.: Characterization of very-low density lipoprotein particle size in egg-laying birds

Avian egg production is dependent on dramatic changes in lipid metabolism, including a marked increase in hepatic production of estrogen-induced, yolk-targeted very-low density lipoprotein (VLDLy). The presence of VLDLy in the plasma represents a shift in hepatic metabolism and synthesis of lipids, as the structure and function of plasma VLDL particles are altered from generic, non-laying VLDL, which is larger in size and is involved in triglyceride transport throughout the body, to VLDLy, which is smaller in size and supplies the yolk with energy-rich lipid. Hepatic production of VLDL in chickens (Gallus gallus domesticus) is thought to switch entirely from generic VLDL to VLDLy during egg production. We therefore attempted to characterize VLDL-VLDLy particle size in laying female Zebra Finches (Taeniopygia guttata) to examine the dynamics of lipid metabolism during egg production in passerines in comparison with chickens. The extent of inter-individual variation in VLDL-VLDLy particle size distribution and cholesterol content, the repeatability of these traits between breeding attempts, and the relationship between these traits and subsequent reproductive effort (i.e., egg and clutch size) will also be described.