Changes in Plasma Lipids during Breeding, Molting, and Starvation in Male and Female Emperor Penguisn (Aptenodytes forsteri)

Abstract

When breeding during the antarctic winter, male emperor penguins support fasts as long as 115 days (pairing, egg brooding, beginning of feeding chicks with esophageal secretion). Similarly, breeding females fast during 45 days from pairing to egg laying. Moreover, both sexes fast for about 1 mo during summer molt. Natural starvation did not seem to self-induce marked changes in plasma lipids (total lipids, TL; triglycerides, TG; phospholipids, PL; total cholesterol, TC), but experimental forced fasting induced a drop in plasma lipids, TC excepted, because of fat store exhaustion. In males, plasma TG were increased by 100% at the time of copulation; all plasma lipids were minimum during mid-incubation, TC excepted, and markedly increased at the time of egg hatching. In breeding females, plasma TL and TG increased tremendously and peaked at the time of copulation, i.e., 10-15 days before laying. In molting birds, all plasma lipids were depressed during feather synthesis and bypassed basal values at the end ...