Meeting Abstract
Elite athletes must eat well so that they acquire the fuels necessary for extreme feats but also so they can contend with the oxidative costs and potential damage associated with peak metabolic performance. Here we show that the energy cost of long-duration flights for a migratory bird is related to the fatty acid composition of fat stores; however, this fat-mediated energy savings during long flight requires birds to contend with increased oxidative damage over the long-term. We used diet manipulations to produce starlings with adipose stores that differed in the relative amounts of certain mono- and polyunsaturated fats (MUFA versus PUFA). These starlings were then flight-trained and successfully flew non-stop for 6 hrs in a windtunnel during which we measured energy expenditure using the doubly-labelled water technique. Starlings with fat stores composed of relatively more of an essential omega-6 PUFA expended 11% less energy during these 6-hr flights than starlings composed of relatively more MUFA; however, this came at an apparent long-term cost in that the omega-6 PUFA-fed birds incurred significantly higher oxidative damage. Our study provides compelling evidence that avian athletes face a considerable tradeoff when deciding what to eat to enhance their performance. This may explain why migratory songbirds carefully discriminate between diets that differ only in their fatty acid composition, and consistently choose a specific ration of 18:2 to 18:1 because it may optimize the energy savings-oxidative cost tradeoff. Supported by NSF (IOS-0748349 to S.R.M. and B.J.P.) and NSC Poland (2015/19/B/NZ8/01394 to U.B.)
