## 4 Discussion
### Physiological Responses
In this study, the animals' HR decreased during both gradual and drastic changes in temperature, with significantly lower HR for drastic change (52.8 beats/minute), suggesting that the decrease in metabolic rate during extreme weather events might have a stronger influence on HR. The HS heart rate identified is lower than those identified in previous studies [35; 36], and these differences might be attributed to the influence of breed and age on HR. The animals from this study averaged 5.5 years of age, which would be considered quite old for wethers. Therefore, it is not surprising that the maximal HR observed in thisstudy was lower than in previous studies using growing animals because maximal heart rates tend to decline with age. A representative assessment of animal core temperature is the rectal temperature. Even under unfavorable climatic conditions, sheep, as strict homeotherms, leverage numerous physiological mechanisms to maintain their body temperature within a relatively narrow range [29]. Previous work has demonstrated that a rise of 1 \({}^{\circ}\)C or less in RT is sufficient to diminish the performance of most livestock [37], especially sheep. Under thermoneutral conditions, sheep have a normal RT range between 38.3 and 39.9 \({}^{\circ}\)C [29], with temperatures exceeding 42 \({}^{\circ}\)C considered dangerous [38]. It has been stated that the rise in RT in sheep starts at an ambient temperature of 32 \({}^{\circ}\)C, with mouth panting beginning at an RT of 40 \({}^{\circ}\)C [39]. In this work, ambient temperature had a significant effect (\(p<0.05\)) on the RT with an increase of 0.3 \({}^{\circ}\)C as animals were gradually adjusted from 20 to 35 \({}^{\circ}\)C. During drastic changes in temperature, the RT increased by nearly twice that (0.6 \({}^{\circ}\)C). These values are still within the normal range for sheep considered to be in the thermoneutral zone. Our findings are consistent with the findings from [39], where HS effects in Merino and Omani sheep in an extensive system were evaluated. Similar results for RT were also found by [40] in Merino sheep under HS conditions in an extensive system. Despite the fact that the mean rectal temperatures observed within the present study were within the normal range, the increase in rectal temperature associated with 35 \({}^{\circ}\)C does suggest animals were experiencing HS conditions. Although the physiological responses of sheep to elevated ambient temperatures are well documented within the literature, these values represent practical challenges because, in extensive production systems, their measurement as a means of determining thermal stress is not practical. In order to monitor HR and RT, in particular, the animal would need to be restrained and often separated from the remainder of the herd, which in and of itself can be a source of stress. As such, practical reliance on HT and RT as a means of diagnosing heat stress will be limited until better technologies for remote monitoring of these physiological parameters becomes available. An alternative to monitoring these physiological parameters is to monitor animal behaviors. Indeed, animals may begin to adapt daily behavioral budgets well before measurable changes in physiological indicators of heat stress are detectable. Therefore, monitoring behavioral characteristics might help to characterize animals experiencing early HS, which may help inform when and where mitigation-related management should be applied.