Effects of temperature acclimation on rabbit metabolic rate and rectal temperature

The metabolic rates and rectal temperatures of cold-(10 degrees C), warm-(20 degrees C) and heat-(30 degrees C) acclimated rabbits were measured at 10, 20 and 30 degrees C. When the logarithm of metabolic rate was plotted against the logarithm of body weight, no differences could be demonstrated between the slopes of the lines obtained for each of the nine experimental groups. Metabolic rate, expressed as kcal h-1 kg-1, kcal h-1 kg-3/4 and kcal h-1 kg-2/3, was mass-independent for most of the experimental conditions. The rabbits were able to maintain constant rectal temperature during cold or heat exposure only when previously acclimated to these temperature extremes. The increase in metabolic rate of cold-acclimated rabbits observed during cold exposure seemed to be too low to explain the maintenance of rectal temperature. The lower metabolic rate of heat-acclimated rabbits exposed to heat probably played an important role in preventing increased rectal temperatures.