Response of dairy cattle to thermal stress: Implications for designing animal breeding strategies for sustainable productivity under changing climate

The objective of this study was to review the response of dairy cattle to heat stress (HS) and assess breeding options for coping with sustainable productivity under a changing climate. High ambient temperature (AT) in combination with relative humidity affects most critical factors for livestock production, such as water availability, animal production, reproduction, and health. When the THI exceeds 72, cows will likely begin experiencing HS, and their in-calf rates will be affected. Several reports have shown the associations of SNPs in HSP genes with the thermal stress response and tolerance in farm dairy cattle. The association of polymorphisms in Hsp90 AB1 with heat tolerance has been reported in Thai native cattle, Sahiwal cattle, and Friesian cattle. Thus, ameliorating HS via physical modifications of the environment, nutrition management, genetic selection, and breeding is paramount. Compared with that of other livestock species, the effect of HS on dairy cattle is a serious problem. Therefore, intensive research under both controlled and on-farm trials is needed. From this review point of view, future research should focus on conservation strategies for locally adaptable breeds with optimum productivity. Moreover, a breeding strategy that considers disease resistance, environmental stress, and adaptation traits should be considered in the future. Furthermore, the regular prediction of environmental stress resulting from climate change and the design of pertinent response strategies are essential for reducing the adverse impacts of environmental stress to increase the resilience capacity of dairy cattle breeds. To promote the conservation of heat-tolerant native breeds, policies and incentives should be designed to address both environmental and economic challenges while recognizing the unique qualities of these breeds. By combining financial support, research, awareness, and market development, policies and incentives can create an environment where heat-tolerant native breeds thrive, contributing to more resilient agricultural systems in the face of climate change.