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COMPARATIVE AND EVOLUTIONARY PHYSIOLOGY

Effect of fasting on the O₂-f_h relationship in king penguins, Aptenodytes patagonicus

¹School of Biosciences and ³School of Mathematics and Statistics, The University of Birmingham, Edgbaston, Birmingham B15 2TT, United Kingdom; ²Centre d'Ecologie et Physiologie Energétiques, CNRS, 67087 Strasbourg Cedex 02; and ⁴Physiologie des Régulations Energétiques, Cellulaires, et Moléculaires, CNRS-Université C. Bernard Lyon, F-69622 Villeurbanne Cedex, France

Submitted 7 November 2003 ; accepted in final form 2 June 2004

King penguins (Aptenodytes patagonicus) may fast for up to 30 days during their breeding period. As such extended fasting may affect the relationship between the rate of O₂ consumption (O₂) and heart rate (f_H), five male king penguins were exercised at various speeds on repeated occasions during a fasting period of 24–31 days. In addition, O₂ and f_H were measured in the same animals during rest in cold air and water (4°C). O₂ and f_H at rest and O₂ during exercise decreased with fasting. There was a significant relation between O₂ and f_H (r² = 0.56) that was improved by including speed, body mass (M_b), number of days fasting (t), and a cross term between f_H and t (r² = 0.92). It was concluded that there was a significant change in the O₂-f_H relationship with fasting during exercise. As t is measurable in the field and was shown to be significant and, therefore, a practical covariate, a regression equation for use when birds are ashore was obtained by removing speed and M_b. When this equation was used, predicted O₂ was in good agreement with the observed data, with an overall error of 3.0%. There was no change in the O₂-f_H relationship in penguins at rest in water.

sea bird; exercise; heart rate technique; metabolic rate; body composition

This article has been cited by other articles:

				A. Fahlman, A. Schmidt, Y. Handrich, A. J. Woakes, and P. J. Butler Metabolism and thermoregulation during fasting in king penguins, Aptenodytes patagonicus, in air and water Am J Physiol Regulatory Integrative Comp Physiol, September 1, 2005; 289(3): R670 - R679. [Abstract] [Full Text] [PDF]