Plasma lipoprotein changes in hens (Gallus domesticus) during an induced molt

Blood plasma lipoproteins were studied during food and light deprivation or prolactin injection-induced involution of ovarian follicles (molt) of laying hens. Egg laying stopped 3 days after initiation of either treatment. Food and light-deprived hens lost 29% of initial body weight during the 10-day experiment (P < 0.05), whereas prolactin-treated hens lost 9% of body weight. Yolk-directed very low density lipoprotein (VLDLy) concentration in plasma decreased in both groups, but declined more rapidly in food and light-deprived hens. Very low density lipoprotein triacylglycerol decreased 40% in food and light-deprived hens by day 2 compared with a 13% decrease in the prolactin-treated hens. By day 5, a lipoprotein particle 21-22 nm in diameter appeared in the d = 1.019-1.046 g/ml density fraction of plasma in both groups. A similar lipoprotein particle, termed HDLR, developed in overfed hens with involuting ovarian follicles. In conclusion, hens undergoing ovarian regression due to food and light deprivation, prolactin treatment or overfeeding display marked decreases in plasma yolk-directed very low density lipoproteins and the appearance of HDLR. Other lipoprotein populations varied depending on whether the hens continued to feed or not.