PRICE, E. R.*; GUGLIELMO, C. G.; University of Western Ontario; University of Western Ontario: Fatty Acid Composition of Muscle Phospholipids in Migratory Sparrows

Migratory birds undergo numerous physiological changes in preparation for the high intensity endurance exercise associated with migration. The fatty acid composition of muscle membranes, particularly the n-6/to n-3 ratio of poly-unsaturated fatty acids, has been shown to affect endurance performance in rats and humans. Fatty acid composition is in turn often affected by diet and exercise regime. We tested the hypothesis that photo-manipulated premigratory birds would adaptively modify muscle membrane fatty acids for endurance performance. In addition, we tested the effect of exercise on fatty acid composition of muscles. Captive white-crowned sparrows were split into three groups, 1) short-day (8L:16D) winter birds without exercise, 2) short-day winter birds with exercise, and 3) long-day (16L:8D) premigratory birds. Exercise caused a large and significant decrease in (n-6)/(n-3) ratio of fatty acids in the pectoralis muscle phospholipids. This result may indicate a depletion of n-6 fatty acids as has been suggested from studies of wild migrants. Light cycle had no significant effect on muscle fatty acid composition, suggesting that birds may not prepare for migration by altering muscle phospholipids. This line of research will help us better understand the constraints on high intensity exercise both in migratory birds and in humans.