Thermoregulatory Response of Blackbelly Adult Ewes and Female Lambs during the Summer under Tropical Conditions in Southern Mexico

SIMPLE SUMMARY: Climate change has intensified high environmental temperatures, subjecting farm animals to heat stress conditions. In this study, the thermoregulatory responses of Blackbelly adult ewes and female lambs, during the summer under tropical conditions, in southern Mexico were analyzed. The combination of temperature and relative humidity in summer in tropical conditions causes heat stress in hair ewes, resulting in thermoregulatory problems. To counteract these effects, females modify their physiological constants to avoid reproductive and productive problems under these production conditions. ABSTRACT: High environmental temperatures cause heat stress in ewes, resulting in thermoregulatory problems. In this study, the thermoregulatory responses of Blackbelly adult ewes (G1, n = 14) and female lambs (G2, n = 7), during the summer under tropical conditions, in southern Mexico were analyzed. Different physiological variables and skin temperatures (ST) of the ewes were recorded. Breathing frequency (BF) values were similar between groups at 116.73 ± 33.598 bpm (G1) and 113.661 ± 34.515 bpm (G2) (p > 0.05). In the case of skin elasticity (SE), there were no significant differences between the time of day and the age of the ewes (p > 0.05). Significant differences were observed between groups for BF, rectal temperature (RT), and heart rate (HR) values (p < 0.05). All ST values, for both groups, were significantly higher during the afternoon (p < 0.001). In general, all Blackbelly adult ewes and female lambs during the summer present severe heat stress conditions as a result of an increase in physiological constants and ST. It is concluded that all ewes thermoregulate body temperature by modifying different physiological variables to counteract the effect of heat stress.