Parâmetros fisiológicos de bovinos cruzados submetidos ao estresse calórico

Abstract

The thermoregulation physiological responses in thermoneutrality and heat stress of crossbred calves (1/2Gir x 1/2Holstein), males and females, with age between 14 and 20 months were studied. The animals were submitted to thermoneutrality (22°C and 70% of relative humidity) and to heat stress (42°C and 60% of relative humidity) in summer and winter season's in bioclimatic chamber. Rectal temperature (TR), respiratory rate (FR) and body surface temperature (BST) were registered at 6 AM and 4 PM. It was observed increase in TR, FR and BST in the heat stress period (P<0.05). TR and FR increased more in the summer than in the winter (P<0.05). No difference between seasons (P>0.05) was observed for BST.