Análise de algumas variáveis fisiológicas para avaliação do grau de adaptação de ovinos submetidos ao estresse por calor

Abstract

It was investigated the rectal temperature, respiratory frequency and total evaporative heat loss rate in Corriedale sheep under three air temperatures, aiming a better comprehension of thermoregulation mechanisms of these animals. Initially, 21 adult animals were housed in climatic chamber under 45°C and variable air humidity (PV), recording the respiratory frequency (FR) and rectal temperature (TR). Basing on the FR and TR, it was selected 10 animals, five of the lowest values, assuming as being the best heat adapted (group 1) and five of the highest values, assuming as the worst heat adapted (group 2). The selected animals were maintained in climatic chamber, where it was measured again TR, FR and total evaporation rate (TET), under 20, 30 and 40°C of air temperature and variable PV. There was no statistical difference between the classified groups, for all the measured variables. In conclusion, the use of the physiological variables TR and FR as mainly parameters for these animals selection, is not enough for evaluate the level of adaptation under high temperatures.