title: Effect of dietary fatty acid composition on depot fat and exercise performance in a migrating songbird, the red-eyed vireo.
abstract: Most migrating birds accumulate lipid stores as their primary source of energy for fueling long distance flights. Lipid stores of birds during migration are composed of mostly unsaturated fatty acids; whether such a fatty acid composition enhances exercise performance of birds is unknown. We tested this hypothesis by measuring metabolic rate at rest and during intense exercise in two groups of red-eyed vireos, a long-distance migratory passerine, fed either a diet containing 82% unsaturated fat (82%U), or one containing 58% unsaturated fat (58%U). Vireos fed the 82%U diet had fat stores containing (77%) unsaturated fatty acids, whereas vireos fed the 58% U diet had fat stores containing less (66%) unsaturated fatty acids. Blood metabolites measured prior to and immediately following exercise confirmed that vireos were metabolizing endogenous fat during intense exercise. Mass-specific resting metabolic rate (RMR) was similar for vireos fed the 58%U diet (2.75+/-0.32 ml O2 g(-1)h(-1)) and for vireos fed the 82%U diet (2.30+/-0.30 ml O2 g(-1) h(-1)). However, mass-specific peak metabolic rate (MR(peak)) was 25% higher in vireos fed the 58%U diet (28.55+/-1.47 ml O2 g(-1) (h-1)) than in vireos fed the 82%U diet (21.50+/-1.76 ml O2 g(-1) h(-1)). Such whole-animal energetic effects of fatty acid composition of birds suggest that the energetic cost of migration in birds may be affected by the fatty acid composition of the diet.
authors.affiliation: Department of Natural Resources Science, University of Rhode Island, Kingston, RI, USA. bjpierce2@yahoo.com
authors.forename: Barbara J
authors.initials: BJ
authors.lastname: Pierce
authors.forename: Scott R
authors.initials: SR
authors.lastname: McWilliams
authors.forename: Timothy P
authors.initials: TP
authors.lastname: O'Connor
authors.forename: Allen R
authors.initials: AR
authors.lastname: Place
authors.forename: Christopher G
authors.initials: CG
authors.lastname: Guglielmo
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D001481:Basal Metabolism; D001774:Blood Chemical Analysis; D001823:Body Composition; D001835:Body Weight; D004041:Dietary Fats / Q000378:metabolism*; D004435:Eating; D004734:Energy Metabolism / Q000502:physiology*; D005227:Fatty Acids / Q000378:metabolism*; D046109:Passeriformes / Q000378:metabolism / Q000502:physiology*; D005082:Physical Exertion / Q000502:physiology*; D012237:Rhode Island
chemical_list: D004041:Dietary Fats; D005227:Fatty Acids