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.

摘要
本研究旨在阐明两种不同环境所提供的微气候，对夏季泌乳期F1 H×Z杂交奶牛生理响应的影响，试验共评估了34头源自4个不同遗传类群的F1 H×Z杂交奶牛。
试验期间，每日测定环境变量：干球温度（dry bulb temperature）、相对湿度（relative humidity）与黑球温度（black globe temperature，BGT），用于计算BGT数值。
分别于每日7:00与14:00采集生理参数：呼吸频率、心率、体表温度、直肠温度及出汗率。
每周称量一次产奶量。
本次评估的F1代奶牛未出现生理变化，泌乳量亦未因养殖环境的差异而出现下降。
尽管BGT达到了被判定为具有应激性的水平（87.7），但试验所用的养殖环境并未对受试动物造成应激，亦未导致其产奶量降低。