Indicadores fisiológicos de vacas Girolando durante o período seco no clima semiárido

Abstract

This study aimed to evaluate the occurrence of heat stress in Girolando dairy cows during the dry season in the Cariri region, located in the semi-arid region of Ceará, Brazil, through the analysis of environmental and physiological variables. The research was conducted under a semi-intensive system, with data collection carried out during morning and afternoon milking periods, including measurements of air temperature, relative humidity, and calculation of the Temperature-Humidity Index (THI), as well as rectal temperature, respiratory rate, and heart rate of the animals. The results showed that THI indicated heat stress conditions in both periods, with higher intensity in the afternoon, characterizing this as the most challenging time for the animals during the dry season. An increase in physiological variables was observed in the afternoon, reflecting the activation of thermoregulatory mechanisms. Despite this, the Girolando cows showed, on average, adaptive capacity to the climatic conditions of the region, maintaining physiological parameters within normal ranges. It is concluded that the afternoon period represents a higher risk of heat stress, highlighting the need for management strategies and improvements in housing from a bioclimatic perspective. Further studies are recommended to better understand physiological responses under semi-arid conditions.