The effects of temperature, relative humidity, wind velocity, and solar radiation in predominantly tropical countries, like Brazil, affect dairy production directly, as the heat tolerance is a serious obstacle to the productive process. The present study objective was to apply the Heat Tolerance Test (HIT) for Girolando cows into two genetic groups and check its use for dairy cattle. The experimental design was randomized assigned that used twenty Girolando cows; ten were 1/2-blood animals and ten were 5/8-consanguinities animals. The HTT was applied over three nonconsecutive days. The test consisted of the evaluation of rectal temperature before and after direct solar radiation exposure for one hour. There was significant statistical difference forHTT (P<0.05) by "t" test for the two genetic groups. The mean values observed for HTT were 9.51 and 9.72, respectively, for the 1/2-blood and 5/8-Girolando cows, indicating the major heat tolerance to the 5/8-Girolando group. By the obtained results, itwas concluded that it's possible to the use the HTT as a tool for selection of dairy cattle pedigree or groups that are more tolerant to heat stress.
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