## 4 Discussion  
### Physiological Responses  
As a response to heat increment, livestock reveals thermoregulatory adaptations such as behavioral, physiological, neuroendocrine, and molecular shifts designed to support the maintenance of body temperature within survivable limits [22]. The physiological responses categorized as respiratory rate, heart rate, rectal temperature, skin temperature, and sweating rate are usually exhibited following behavioral responses [23]. In the present study, an assessment of animal responses such as behavior (lying, standing, eating, ruminating responses), respiration, heart rate, and rectal temperature of sheep undergoing heat stress were collected. The animals showed higher RR and RT when the temperature was drastically changed to 35 \({}^{\circ}\)C in comparison with gradually changing temperature, suggesting that the effect of HS on RR and RT is amplified during extreme weather events. When developing management strategies to support climate-smart agriculture, specific mitigation approaches for extreme weather events may be necessary. Despite thermo-regulatory responses, animals' productivity tends to decrease during summertime [24]. In the United States, both large and small sheep farms rely heavily on pasture-based systems, with the large scale typically operating on pasturelands and the smaller farms maintained on pastures and feedlots [25]. The outdoor housing systems used in the sheep industry increase the susceptibility to climate-related stress, specifically heat stress, thereby increasing their vulnerability to such impacts [26; 27; 28]. Therefore, mitigation strategies and technologies to help minimize the negative impact of heat stress on sheep will be necessary to maintain the resilience of this industry as the climate changes. Increased RR is a very sensitive and widely used indicator of heat stress [3]. In ruminants, RR can be influenced by several factors, including the level of production, body condition, housing, cooling systems, and prior exposure to high temperatures [3]. Sweating and evaporation through the respiratory tract are the most important mechanisms of heat exchange between the sheep and its environment, with sweating being secondary due to the presence of wool [29]. In sheep, the normal respiratory rate is typically between 20 and 38 BrPM [30]. In this study, mean respiratory rates increased when the ambient temperature was gradually increased (17.9 vs. 66.0 BrPM), and there was a marked increase when the temperature underwent drastic changes (90.2 BrPM). However, the respiratory mean at 27 \({}^{\circ}\)C was similar, suggesting that sheep leverage changes in RR at temperatures higher than 27 \({}^{\circ}\)C.  
Similar results for RR in Suffolk sheep were demonstrated by [31], who evaluated the effects of HS in different sheep breeds in tropical regions. Because RR changes were not observed at intermediate temperatures, this physiological indicator may be an insensitive strategy to identify low-to-moderate stress instances associated with elevated but not excessive ambient temperatures. For reference, a RR of 60 to 80 BPM is typically considered medium to high stress [32]. High environmental temperatures also increase pulse rates, reflecting altered circulation as a response to the increase in blood flow from the core to the periphery [29]. However, at extremely high temperatures, due to the decrease in the metabolic rate, the pulse rate might drop [33]. Moreover, heart rate is influenced by other factors such as age, metabolism, and biological activity [27]. The authors in [34] evaluated the responses of Merino sheep (average age of 12 months) under HS conditions and found an increase in HR up to 109 BPM when animals were exposed to 30 \({}^{\circ}\)C in an environmentally controlled experimental room.