Physiological parameters of F1 Holstein X Zebu cows raised in environments with and without shading

ABSTRACT The objective of this study was to characterize the effect of microclimate provided by two distinct environments on the physiological responses of F1 HxZ cows lactating during the summer, where 34 cows were evaluated originating from 4 different genetic groups F1 HxZ. During the trial period, daily measurements of environmental variables were determined: dry bulb temperature, relative humidity and black globe temperature, to calculate the BGT values. The physiological parameters respiratory rate, heart rate, body surface temperature, rectal temperature, and sweat rate were obtained at 07:00 and 14:00h. Weighing of milk was done weekly. The F1 animals evaluated did not present physiological changes, nor was there a reduction in milk production as a function of breeding environments. The BGT reached levels considered stressful (87.7), but the breeding environments provided no stress or reduced production of animals.