This study aimed to characterize the adaptive profiles and thermoregulatory status of Hararghe Highland (HH) sheep across two distinct seasons through evaluating physiological parameters. Fifty-four healthy adult HH sheep were evaluated for body surface temperature (BST), rectal temperature (RT), respiratory rate (RR), heart rate (HR), and pulse rate (PR), with measurements taken twice daily during both seasons across three agroecological zones. Ten heat stress indices, including climate-based (THI, THIn, CCCIg, CCCIe, CCCIp) and physiology-based (ECIg, ECIe, ECIp, IHTI, BHTI), were computed to assess the environmental thermal load and its impact on the physiological heat stress responses of HH sheep using linear mixed models. The results indicated significant effects (p 0.05). Afternoon values were consistently higher than morning values across all parameters (BST: 37.6 vs. 36.6°C; RT: 38.1 vs. 37.5°C; RR: 28.8 vs. 23.9 breaths/min; HR: 83.4 vs. 77.3 beats/min; PR: 80.3 vs. 74.2 pulsations/min), and dry-season values exceeded wet-season values for all parameters. Correlational analysis revealed that, except for IHTI and BHTI, most indices showed strong positive associations with physiological parameters (r = 0.63–0.94), confirming their applicability for evaluating environmental heat load in HH sheep. Climate-based indices (THI, THIn, CCCIp) are recommended for on-farm heat stress monitoring without requiring animal measurement. These findings provide a foundation for evidence-based heat stress management and conservation of locally adapted genetic resources under climate change.
Yousuf et al. (Mon,) studied this question.