The effect of simulated altitude on the heat increment of feed in sheep

1. Sheep given constant feed were exposed to environments in which the oxygen concentration in air was either 200 or 150 ml/l. There were no differences in daily heat production, methane production, urinary energy or faecal energy losses measured over periods of 4 d. 2. When the sheep were fasted there were no differences in heat production to be ascribed to the O2 concentration in air. The thermic response to feed was unaffected by the O2 concentration in the air.