Sources of inter- and intra-individual variation in basal metabolic rate in the zebra finch, Taeniopygia guttata

We investigated the physiological background to individual variation in basal metabolic rate (BMR) in a laboratory population of a small passerine bird, the Zebra finch, Taeniopygia guttata. We especially explored whether food-quality during early development influenced the BMRlater in life. Zebra finches were raised on two different food regimes; one (dlow qualityT) involvingonly mixed seed diet, while the other (dhigh qualityT) in addition including a protein supplement and daily fresh hard-boiled eggs. The different diets were administrated to the birds only during the first 6 weeks of life. At an age of 1.5 to 2 years, and after a breeding period of their own, BMR was measured in all individuals. Food quality had a significant effect on body mass. Adult finches raised on high-quality protein-rich food were significantly heavier (2.2 g for males and 1.9 g for females) than their counterparts raised on low-quality food. Despite this, the BMR of the adult birds did not differ beyond that expected based on variation in body mass alone. Hence, the early feeding regimes, which induced a non-genetic phenotypic variability in body mass, did apparently not induce any long-term changes in body composition or in organ metabolic intensity. D 2004 Elsevier B.V. All