ICAR-National Institute of Animal Nutrition and Physiology, Adugodi, Hosur Road, Bangalore, Karnataka, 560030, India.
Academy of Climate Change Education and Research, Kerala Agricultural University, Vellanikkara, Thrissur, Kerala, India.
Int J Biometeorol. 2019 Sep;63(9):1265-1281. doi: 10.1007/s00484-019-01735-9. Epub 2019 May 26.
Livestock industries have an important role in ensuring global food security. This review discusses the importance of quantifying the heat stress response of ruminants, with an emphasis on identifying thermo-tolerant breeds. There are numerous heat stress prediction models that have attempted to quantify the response of ruminant livestock to hot climatic conditions. This review highlights the importance of investigating prediction models beyond the temperature-humidity index (THI). Furthermore, this review highlights the importance of incorporating other climatic variables when developing prediction indices to ensure the accurate prediction of heat stress in ruminants. Prediction models, particularly the heat load index (HLI) were developed to overcome the limitations of the THI by incorporating ambient temperature (AT), relative humidity (RH), solar radiation (SR) and wind speed (WS). Furthermore refinements to existing prediction models have been undertaken to account for the interactions between climatic variables and physiological traits of livestock. Specifically, studies have investigated the relationships between coat characteristics, respiration rate (RR), body temperature (BT), sweating rate, vasodilation, body weight (BW), body condition score (BCS), fatness and feed intake with climatic conditions. While advancements in prediction models have been occurring, there has also been substantial advancement in the methodologies used to quantify animal responses to heat stress. The most recent development in this field is the application of radio frequency identification (RFID) technology to record animal behaviour and various physiological responses. Rumen temperature measurements using rumen boluses and skin temperature recording using infrared thermography (IRT) are making inroads to redefine the quantification of the heat stress response of ruminants. Further, this review describes several advanced biotechnological tools that can be used to identify climate resilient breeds of ruminant livestock.
畜牧业在确保全球粮食安全方面发挥着重要作用。本综述讨论了量化反刍动物热应激反应的重要性，重点是确定耐热品种。有许多热应激预测模型试图量化反刍家畜对炎热气候条件的反应。本综述强调了超越温湿度指数（THI）研究预测模型的重要性。此外，本综述还强调了在开发预测指数时纳入其他气候变量的重要性，以确保对反刍动物热应激的准确预测。预测模型，特别是热负荷指数（HLI）的开发是为了通过纳入环境温度（AT）、相对湿度（RH）、太阳辐射（SR）和风速（WS）来克服 THI 的局限性。此外，还对现有的预测模型进行了改进，以考虑气候变量和家畜生理特征之间的相互作用。具体而言，研究已经调查了毛发生长特性、呼吸率（RR）、体温（BT）、出汗率、血管扩张、体重（BW）、体况评分（BCS）、肥胖和饲料摄入与气候条件之间的关系。虽然预测模型的进展一直在发生，但用于量化动物对热应激反应的方法也取得了实质性进展。该领域的最新进展是应用射频识别（RFID）技术来记录动物行为和各种生理反应。使用瘤胃球囊测量瘤胃温度和使用红外热成像（IRT）记录皮肤温度正在重新定义反刍动物热应激反应的量化。此外，本综述还描述了几种可用于识别反刍家畜耐热品种的先进生物技术工具。
