Meeting Abstract
Diet quality, in addition to quantity, is an often-overlooked factor that can influence the performance and success of animals. In particular, diet fatty acid composition has been related to metabolic performance in a wide range of taxa. However, the continuity of these effects over different measures of performance, interactions with seasonal changes in life-history stages, and the role of specific fatty acids remain relatively unknown. We tested the effect of dietary linoleic acid (LA) on basal and peak metabolic rates, flight duration, energy expenditure, and rates of fat and lean catabolism during a voluntary wind-tunnel flight, and the activity of the metabolic enzymes CPT, HOAD, CS, and LDH over the course of a simulated fall migratory period in European Starlings. We found a consistent interaction between diet and season influencing metabolic rates and long-flight performance, with birds fed high-LA diets decreasing in metabolic rates and rates of energy expenditure and fat catabolism over the course of the fall season and low-LA birds increasing in those measures. Enzyme activity did not display this interaction, but did increase over the season for CPT, HOAD, and LDH. CPT activity was positively related to flight duration and rate of fat catabolism. These results indicate that the influence of dietary LA on metabolic performance is contingent on seasonal progression and that changes in whole-animal performance are likely mediated by tissue-level changes in metabolic enzyme activity and density.
