Relationships between energy intake and body mass in captive animals

Abstract

Basal metabolism and energy intake in relation to body mass have long been studied in domestic animals; however, there are few studies on energy intake in captive wild animals. A total of 35 species were studied, including a wide variety of body size ranging from black kite (approx. 0.7kg) to whale shark (approx. 1200kg) kept at zoos and aquariums. Based on feeding contents, we here estimated the energy intake of mammals, birds, reptiles, amphibians, fish and cephalopods. The ratios of food mass to body mass were 7.5% and 12.9% in mammals and birds, respectively, whereas the ratios were smaller than 1% in reptiles, amphibians, fish and cephalopods. The mass-specific energy intake took a value of 100kcal/d in homeotherms (mammals and birds), whereas it took a value of smaller than 15kcal/d in poikilotherms. The energy intake increased with body mass in a proportional manner, suggesting that the energy intake of captive animals could be simply estimated from body mass.