Meeting Abstract
Obesity is a major issue in modern human societies, in part linked to diet. Humans consuming more calories through eating highly-processed foods or high fat diets gain weight. Although some birds show marked seasonal fluctuations in body (fat) mass, e.g. migrants, many birds appear to tightly regulate body mass and don’t get fat. Yet studies on the underlying mechanisms of mass regulation in these non-migrant birds are scarce. We attempted to make captive zebra finches fat by providing them with a high fat diet ad lib for 3 weeks. Birds consumed the high-fat food, and they had elevated plasma triglyceride levels, but there was no associated change in body mass. Birds had mean plasma triglyceride levels ~6-8 mmol/l but three apparently-healthy individuals had triglyceride levels > 60 mmol/l perhaps indicating an interesting “high-fat” phenotype. Body mass was highly variable among individuals, even controlling for structural size, and was highly repeatable at all stages of the experiment. However, birds showed little diurnal variation in body mass, which is common in free-living birds. The only major perturbation of body mass occurred when all birds were blood sampled (-3%), but individual birds returned to pre-sampling mass within 4-5 days, with high repeatability – again suggesting tight regulation of body mass. Zebra finches did show a significant reduction in body mass when exposed to visual and audio cues from a model barn owl – suggesting they retain the potential for ‘strategic’ regulation of mass in relation to certain cues (here a predator). Despite their unnatural habitat captive zebra finches might provide an interesting model to explore mechanisms that prevent some birds from getting fat.
