Heat production by the mature male turkey (Meleagris gallopavo): preliminary measurements in an automated, indirect, open-circuit multi-calorimeter system.

The energy metabolism of mature male turkeys (Meleagris gallopavo) was determined in a computer-controlled indirect multi-calorimeter system of which the design and operation are described. Daily heat production did not change significantly during an initial 6-d period in the calorimeter chambers. Food intake was at first sufficient to promote a rate of energy retention significantly greater than zero, but decreased to give negative energy retention on day 6; mean energy retention for the whole 6-day period was significantly greater than zero. Heat production was affected little by fasting for 72 h, although the respiratory quotient decreased to 0.72 within 48 h; the heat increment of feeding was therefore small (about 5% of metabolisable energy). Fasting heat production, scaled on metabolic body size (bodyweight in kg)0.75, was similar to that of mature male domestic fowl (Gallus domesticus). Heat production after refeeding was similar to that recorded during the 6 d before fasting. There was a pronounced circadian rhythmicity of heat production in both fed and fasted birds.