Comparison of Rectal and Deep Body Temperature in the Calf

Abstract

IN the bovine animal as with other domestic mammals including man, the rectal temperature is generally accepted as a measure of deep body temperature, and it is widely used both in field and laboratory studies for indicating the state of thermal balance of cattle when subjected to climatic stress. Despite the possibility of thermal gradients within the rectum, as has been found in man¹, there is no obvious reason for doubting the validity of this assumption, at least as an approximation, when body temperatures are steady. However, under conditions of thermal stress, when body temperatures are rising, a constant and close relationship between rectal and deep-body temperature cannot be assumed, as there is almost certainly a delay before the temperature of the fæcal mass reaches equilibrium with that of the rectal wall. Consequently, an investigation has been made ta study the validity of using rectal temperature as a measure of deep body temperature in Ayrshire bull calves, four to six months old. Cattle of this age and breed have already been used in studies of environmental physiology in a climatic chamber in this Institute².