## 4 Discussion
### Effects of Temperature on Animal Behavior  
An animal's physical state can be inferred from its action, which allows using animal behavior as an indicator of welfare [41]. The variability in behavior, the length of behavioral bouts, and the transition frequencies between activities and rest can be altered by HS [41]. To quantify those changes, behavior can be recorded continuously or sampled at regular intervals and can be characterized by metrics on individual activities or a complete ethogram of an individual or group [42]. The number of bouts, time per bout, and total time that animals spent in each behavior are presented in Table 5.  
Behavioral responses to HS have been previously investigated in ruminants, mainly in cattle. Generally, the behaviors of interest involve dry matter intake (DMI) measurements. Even a slight rise in ambient temperature from 25 to 27 \({}^{\circ}\)C has been shown to decrease DMI in dairy cattle [43]. Collectively, the DMI responses to HS support the notable negative impact on health and production [23]. This influence of the thermal environment on HS exemplifies the challenge of waiting until clinical HS symptoms appear to apply stress abatement. Although the decrease in DMI is important for modulating the depressed productivity of HS animals, studies involving pair-fed thermal neutral controls reveal that the reduced DMI contributed to only \(\sim\)50% of the decrease in productivity related to milk production in dairy cows [44]. Residual changes in productivity could be due to shifts in pre- or post-absorptive metabolism [45]. Measuring DMI was not an objective of this study. However, bouts, time per bout, and length of eating were lower in high ambient temperatures (Table 5), which is consistent with impaired eating behavior and reduced DMI in heat-stressed animals.  
Measures of lying and standing behaviors are indicators of animal welfare and how animals interact with the environment [46; 47; 48]. Increased standing time was believed to be a response to heat stress in cattle driven by the need to expose more surface area and enhance cooling [13; 49; 50] with decreasing lying bouts as a consequence. Despite the fact that an increase in the total time standing was significantly associated with elevated ambient temperatures in this study, animals spent the majority of their time lying down. This large daily time budget for lying behavior is in contradiction with the literature. For example, [51] evaluated lying time and frequency as a behavioral response of HS in Holstein bull calves using an accelerometer and found that an increase in lying time and frequency during the daytime was possibly caused by acute HS. A possible explanation for the notable difference in daily time budgets measured in this study may reflect the age of animals and their comfort with experimental procedures. The sheep used in this work have been involved in numerous intensive research projects since their cannulation at 15 to 17 months of age. Their old age in the present study, coupled with habituation to experimentation, may have supported improved comfort with the experimental procedures supporting elevated lying time budgets observed herein. The fact that animals increased total standing time with elevated temperatures is likely the best reflection within the behavioral observations of animals' behavioral adaptation to heat stress.