School of Agriculture and Food, Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Melbourne, VIC, 3010, Australia.
ICAR National Institute of Animal Nutrition and Physiology, Bangalore, India.
Int J Biometeorol. 2021 Jul;65(7):1231-1244. doi: 10.1007/s00484-021-02083-3. Epub 2021 Jan 26.
Heat stress is one of the greatest challenges for the global livestock industries as increased environmental temperature and humidity compromises animal production during summer leading to devastating economic consequences. Over the last 30 years, significant developments have been achieved in cooling and provision of shade and shelter to mitigate heat stress reducing some of the losses associated with heat stress in farm animals. However, the recent increase in the incidence of heat waves which are also becoming more severe and lasting longer, due to climate change, further accentuates the problem of heat stress. Economic losses associated with heat stress are both direct due to loss in production and animal life, and indirect due to poorer quality products as a result of poor animal health and welfare. Animal health is affected due to impaired immune responses and increased reactive oxygen species production and/or deficiency of antioxidants during heat stress leading to an imbalance between oxidant and antioxidants and resultant oxidative stress. Research over the last 20 years has achieved partial success in understanding the intricacies of heat stress impacts on oxidative stress and immune responses and developing interventions to ameliorate impacts of heat stress, improving immune responses and farm animal health. This paper reviews the body of knowledge on heat stress impacts on immune response in farm animals. The impacts of heat stress on both cell-mediated and humoral immune responses have been discussed identifying the shift in immune response from cell-mediated towards humoral response, thereby weakening the immune status of the animal. Both species and breed differences have been identified as influencing how heat stress impacts the immune status of farm animals. In addition, crosstalk signaling between the immune system and oxidative stress has been considered and the role of antioxidants as potential nutritional strategies to mitigate heat stress has been discussed.
热应激是全球畜牧业面临的最大挑战之一，因为环境温度和湿度的升高会在夏季影响动物生产，导致灾难性的经济后果。在过去的 30 年中，在冷却、提供阴凉和遮蔽物以减轻热应激方面取得了重大进展，从而减少了与农场动物热应激相关的一些损失。然而，由于气候变化，近年来热浪的发生率有所增加，而且热浪变得更加严重和持久，进一步加剧了热应激问题。与热应激相关的经济损失既有直接损失（由于生产和动物生命的损失），也有间接损失（由于动物健康和福利较差导致产品质量下降）。动物健康受到影响是由于热应激导致免疫反应受损、活性氧物质产生增加和/或抗氧化剂缺乏，从而导致氧化剂和抗氧化剂之间失衡以及由此产生的氧化应激。过去 20 年的研究在理解热应激对氧化应激和免疫反应的影响以及开发缓解热应激影响、改善免疫反应和农场动物健康的干预措施方面取得了部分成功。本文综述了关于热应激对农场动物免疫反应影响的知识体系。讨论了热应激对细胞介导和体液免疫反应的影响，确定了免疫反应从细胞介导向体液反应的转变，从而削弱了动物的免疫状态。已确定物种和品种差异会影响热应激对农场动物免疫状态的影响。此外，还考虑了免疫系统和氧化应激之间的串扰信号，以及抗氧化剂作为缓解热应激的潜在营养策略的作用。
