Multivariate analysis of the behavior and physiology of Girolando heifers in pasture

ABSTRACT The objective of this study was to evaluate the thermal effect on the behavioral and physiological changes of Girolando heifers by means of principal components analysis. The research was conducted in the Agreste region of the state of Pernambuco, Brazil. Three heifers submitted to the continuous grazing system were used. For the determination of the thermal effect on the animals, the variables dry bulb temperature and relative air humidity were recorded, which allowed to determine the temperature and humidity index and the specific enthalpy. The physiological variables monitored were the respiratory rate, rectal temperature and skin temperature. The quantified behavioral indicators were walking, drinking, eating, ruminating and leisure, to determine the percentage of time spent in each behavior. The variables of the study were submitted to exploratory and descriptive analysis, in order to infer the degree of association of the main components. The multivariate analysis allowed to establish the degree of pertinence between the physiological signs and behavioral patterns associated with the thermal environment, which indicated heifers adaptation to continuous grazing, even in critical meteorological conditions.

摘要：本研究旨在通过主成分分析，评估热环境对吉兰朵小母牛（Girolando）行为与生理变化的影响。研究于巴西伯南布哥州阿格里什蒂（Agreste）地区开展，试验选用3头采用连续放牧系统饲养的吉兰朵小母牛。为测定热环境对试验动物的影响，研究记录了干球温度与空气相对湿度两项环境参数，据此计算得到温湿度指数与比焓。本研究监测的生理指标包括呼吸频率、直肠温度与皮肤温度；量化的行为指标涵盖行走、饮水、采食、反刍与休憩，以此统计各行为的耗时占比。研究对所有变量开展探索性与描述性分析，以推断主成分间的关联程度。通过多元分析明确了与热环境相关的生理体征与行为模式间的关联程度，结果表明即便在严苛气象条件下，吉兰朵小母牛仍可适应连续放牧饲养模式。