title: Validation of the doubly labeled water method in bald eagles (Haliaeetus leucocephalus) and a comparison of two equations for the calculation of energy expenditure.
abstract: We validated the doubly labeled water (DLW) technique for measurement of energy expenditure in bald eagles (Haliaeetus leucocephalus) in captivity by simultaneously measuring metabolizable energy intake in a feeding trial. We calculated CO2 production using two equations, one typically used by animal ecologists (the "one-pool" equation) and the other typically used by human nutritionists (the "two-pool" equation). Metabolizable energy intake, as determined by feeding trials, for two adult eagles eating rats averaged 1,160 +/- 89 kJ d-1 and for four nestlings eating fish averaged 2,124 +/- 40 kJ d-1. Energy expenditure measured from DLW turnover using the one-pool equation averaged 2.2% +/- 7.1% higher than metabolizable energy intake measured by feeding trials (not significantly different, P > 0.50), but when the two-pool equation was used, energy expenditure measured with DLW averaged 17.7% +/- 6.7% lower than metabolizable energy intake measured by feeding trials (significantly different, 0.025 < P < 0.05). Thus, the use of the DLW technique with CO2 production calculated by the one-pool equation was validated for bald eagles.
authors.affiliation: Department of Wildlife Ecology, University of Wisconsin, Madison 53706, USA. dykstra.cheryl@epamail.epa.gov
authors.forename: C R
authors.initials: CR
authors.lastname: Dykstra
authors.forename: M W
authors.initials: MW
authors.lastname: Meyer
authors.forename: W H
authors.initials: WH
authors.lastname: Karasov
mesh_terms: D000818:Animals; D001717:Birds / Q000378:metabolism* / Q000502:physiology; D015992:Body Mass Index; D002245:Carbon Dioxide / Q000378:metabolism*; D002247:Carbon Isotopes; D003903:Deuterium; D004435:Eating / Q000502:physiology; D004734:Energy Metabolism / Q000502:physiology*; D005260:Female; D008297:Male; D008722:Methods; D010103:Oxygen Isotopes; D015203:Reproducibility of Results
chemical_list: D002247:Carbon Isotopes; D010103:Oxygen Isotopes; D002245:Carbon Dioxide; D003903:Deuterium