The role of water for heat dissipation by a Jersey cow and a Corriedale ewe.

Abstract

Experimental climatological work was carried out on a Jersey cow and a Corriedale ewe. These animals were exposed to a series of controlled environmental conditions in a psychrometric room for periods of 7 hr and their reactions observed. Both animals showed an increase in body temperature, respiratory rate and volume, and respiratory and transcutaneous water losses during heat exposure. Values and trends in these reactions were calculated for each exposure. Transcutaneous water loss by unit area of Jersey cow skin was of the same order as loss through human skin. Respiratory water loss formed only a small fraction — a fifth to a ninth — of the total water loss. In the sheep, however, respiratory water loss reached as much as one-third of the total water loss and the transcutaneous loss was one-third of that through human skin. It was concluded that the Jersey cow efficiently maintained a heat balance presumably by a good sweating mechanism. The Corriedale ewe, however, was a poorly sweating ruminant, relying mainly on the respiratory mechanism for approaching a heat balance.