Department of Animal Production, College of Food and Agriculture Sciences, King Saud University, P.O. Box 2460, Riyadh, 11451, Saudi Arabia.
J Therm Biol. 2024 Oct;125:103960. doi: 10.1016/j.jtherbio.2024.103960. Epub 2024 Aug 18.
Infrared thermography (IRT) is an essential non-invasive method for analyzing surface temperature variations in animals, offering valuable insights into livestock stress responses. Despite their resilience, goats can face significant challenges under extreme conditions like heat-stress and water deprivation. This experiment aimed to delineate the dynamic variations in whole-body and scrotal surface temperatures in goats subjected to the combined impact of both conditions using IRT. Eight healthy Aardi bucks were exposed to three 72-h treatments: euhydration, dehydration, and rehydration. Continuous meteorological monitoring provided ambient-temperature, relative-humidity, and temperature-humidity index (THI) values. Surface temperatures were measured twice daily at 08:00 and 15:00, and thermal gradients between ambient and body or scrotal surface temperatures were computed. Based on the obtained mean THI values, the bucks experienced heat-stress throughout the experiment. Additionally, results revealed noticeable variations in both surface temperatures across treatments and time points, indicated by measures of central tendency, variability, shape descriptors, and frequency distribution of temperature. Morning measurements indicated lower temperatures and gradients under euhydration, while water deprivation led to higher temperatures and compromised thermal regulation. Conversely, afternoon data showed higher variability in temperature responses, highlighting the compounded effect of diurnal heat-stress and water deprivation. Although water-restoration mitigated some effects of deprivation, it did not fully restore thermal homeostasis to euhydrated levels. Thermal gradients further emphasized the goats' dynamic thermoregulatory mechanisms, which were compromised under water deprivation, particularly in the scrotal region, but were partially restored upon restoration. These findings demonstrate the effectiveness of IRT in assessing thermal responses in goats and underscore the importance of adequate hydration for maintaining thermal balance under heat-stress. The herein performed profiling provides valuable insights with implications for overall health, reproductive efficiency, productivity, and welfare in heat-stressed and water-deprived goats, which might offer a framework for future research on livestock adaptation to such challenging environmental conditions.
红外热成像（IRT）是分析动物表面温度变化的一种基本的非侵入性方法，可以深入了解家畜的应激反应。尽管山羊具有很强的适应能力，但在热应激和缺水等极端条件下，它们仍会面临重大挑战。本实验旨在利用 IRT 描绘受到这两种情况综合影响的山羊全身和阴囊表面温度的动态变化。八只健康的 Aardi 公山羊分别暴露于三种 72 小时的处理条件下：水合、脱水和再水合。连续的气象监测提供了环境温度、相对湿度和温湿度指数（THI）值。每天在 08:00 和 15:00 测量两次表面温度，并计算环境温度与身体或阴囊表面温度之间的热梯度。根据获得的平均 THI 值，整个实验期间公山羊都经历了热应激。此外，结果表明，在整个实验过程中，不同处理和时间点的表面温度都发生了明显的变化，表现在集中趋势、变异性、形状描述符和温度的频率分布上。水合组早上的测量结果表明温度和梯度较低，而在缺水组中，温度较高，且热调节受损。相反，下午的数据显示出温度响应的更大变异性，突出了昼夜热应激和缺水的复合影响。尽管水的恢复减轻了缺水的一些影响，但并未完全将热平衡恢复到水合状态。热梯度进一步强调了山羊动态热调节机制，在缺水条件下，特别是在阴囊区域，这些机制受到了影响，但在恢复后得到了部分恢复。这些发现表明 IRT 在评估山羊的热反应方面非常有效，并强调了在热应激下保持充足水合对于维持热平衡的重要性。本文进行的分析提供了有价值的见解，对热应激和缺水的山羊的整体健康、繁殖效率、生产力和福利具有重要意义，并为未来研究家畜对这种具有挑战性的环境条件的适应提供了框架。
