Energetics of a long-distance migrant shorebird (Philomachus pugnax) during cold exposure and running.
The metabolic consequences of cold exposure and exercise are not well characterized in birds. Ruff sandpipers Philomachus pugnax are migrant shorebirds traveling between Africa and Siberia for up to 30,000 km annually. Our goal was to quantify the fuel selection pattern of these remarkable athletes during shivering and terrestrial locomotion. We used indirect calorimetry and nitrogen excretion analysis to measure their rates of lipid, carbohydrate and protein oxidation at different temperatures (22, 15, 10 or 5 degrees C) and different treadmill speeds (15, 20, 25, 30, 35 or 40 m min(-1)). Results show that lipid oxidation supplies nearly all the energy necessary to support shivering and running, and that the pattern of oxidative fuel selection is independent of shivering or running intensity. During shivering, total ATP production is unequally shared between lipids (82%), carbohydrates (12%) and proteins (6%). During running, lipids remain the dominant substrate (66%), with carbohydrates (29%) and proteins (5%) playing more minor roles. The prevailing use of lipids during intense shivering and high-speed running is not consistent with the fuel selection pattern observed in exercising and cold-exposed mammals. The exact mechanisms allowing birds to use lipids at extremely high rates are still largely unexplored, and quantifying the relative importance of different fuels during long-distance flight remains a major challenge for future research.
Vaillancourt
Eric
E
Biology Department, University of Ottawa, Ottawa, Ontario, Canada.
Prud'homme
Sophie
S
Haman
François
F
Guglielmo
Christopher G
CG
Weber
Jean-Michel
JM
D000064:Acclimatization / Q000502:physiology*; D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D002153:Calorimetry, Indirect; D050260:Carbohydrate Metabolism; D046091:Charadriiformes / Q000502:physiology*; D003080:Cold Temperature; D004734:Energy Metabolism / Q000502:physiology*; D050356:Lipid Metabolism; D009584:Nitrogen / Q000378:metabolism; D005082:Physical Exertion / Q000502:physiology*; D011506:Proteins / Q000378:metabolism; D013696:Temperature
D011506:Proteins; D000255:Adenosine Triphosphate; D009584:Nitrogen