Department of Veterinary and Animal Sciences, University of Copenhagen, Grønnegårdsvej 2, 1870 Frederiksberg C, Copenhagen, Denmark.
Department of Veterinary and Animal Sciences, University of Copenhagen, Grønnegårdsvej 2, 1870 Frederiksberg C, Copenhagen, Denmark.
J Therm Biol. 2022 Feb;104:103142. doi: 10.1016/j.jtherbio.2021.103142. Epub 2021 Dec 1.
Global warming combined with increased production (i.e. more piglets, more milk and consequently more heat) means that sows are more often challenged by heat stress. The objective was to develop an effective temperature (ET) equation to predict how air temperature, velocity and humidity affect the respiration rate (RR), rectal temperature (RT) and skin temperature (ST) as an expression of heat stress in gestating sows in order to elucidate the relationship between the thermal parameters and the sows' perception of the environment. The experimental room was equipped with a negative pressure ventilation system with diffuse air inlet through the ceiling, electrical heaters, steam generators and dehumidifiers. An air distribution unit was constructed to generate vertical air velocity. A total of 16 gestating sows were exposed to three temperatures (25°C, 29°C and 33°C), two levels of relative humidity (30% and 70%) and three levels of air velocity (0.2 ms, 1 ms and 2.5 ms). The RR, RT and ST were recorded every 30 min throughout the three 2-h test periods. The estimated effects of humidity and velocity in relation to effect of temperature was nearly independent of whether it was determined from RR or RT, whereas the effect of humidity was much smaller when determined from ST. High coefficients of determination (>0.97) were found for the second order relationship between the estimated ET and RR, RT and ST. An increase in relative humidity from 50 to 70% corresponded to an increase in ET of 0.9°C, while an increase in air velocity from 0.2 to 1.0 ms corresponded to a decrease in ET of 1.2°C. The applied ET equation was useful for expressing the combined effect of temperature, humidity and velocity on animals exposed to heat stress. However, multiplying the effect of velocity by the temperature gradient between the animal and the surrounding air did not improve the estimation.
全球变暖加上产量增加（即更多的仔猪、更多的牛奶，因此产生更多的热量）意味着母猪更容易受到热应激的影响。目的是开发一种有效的温度（ET）方程，以预测空气温度、速度和湿度如何影响呼吸率（RR）、直肠温度（RT）和皮肤温度（ST），作为妊娠母猪热应激的表达，以阐明热参数与母猪对环境感知之间的关系。实验室内配备了负压通风系统，空气通过天花板扩散进入，配备了电加热器、蒸汽发生器和除湿器。构建了一个空气分配单元以产生垂直空气速度。共有 16 头妊娠母猪暴露在三种温度（25°C、29°C 和 33°C）、两种相对湿度（30%和 70%）和三种空气速度（0.2 ms、1 ms 和 2.5 ms）下。在三个 2 小时测试期间，每 30 分钟记录一次 RR、RT 和 ST。湿度和速度的影响与温度的影响几乎是独立的，无论它是从 RR 还是 RT 确定的，而湿度的影响从 ST 确定时要小得多。RR、RT 和 ST 的二次关系的估计效果与 ET 之间存在高度的相关性（>0.97）。相对湿度从 50%增加到 70%，相当于 ET 增加 0.9°C，而空气速度从 0.2 增加到 1.0 ms，相当于 ET 减少 1.2°C。应用的 ET 方程可用于表达温度、湿度和速度对暴露于热应激的动物的综合影响。然而，将速度的影响乘以动物与周围空气之间的温度梯度并没有提高估计的准确性。
