Applications of Genetic Selection in Breeding for Thermo-Tolerance in Livestock

Climate change and rising global temperature are expected to exacerbate further the problem of heat stress which is very well known to affect livestock production, reproduction, and welfare negatively. Despite the tremendous advances in strategies to alleviate the impact of heat stress on livestock production, heat stress remains a substantial challenge for sustainability of global livestock production causing substantial economic losses to livestock industries in the warmer parts of the world. Physical modification of the environment, nutritional interventions, and genetic selection for heat tolerance are strategies that could be used to attenuate some of the negative impacts of heat stress. While genetic selection for heat tolerance would be the best long-term strategy to produce heat resilient future animals, identification of heat-tolerant animals is a big challenge due to the negative association between production traits and heat tolerance. Due to this unfavorable correlation between production traits and heat tolerance, a sustained reduction in heat tolerance has occurred due to continuous selection for increased production over the last 50 years. More work is thus needed to find phenotypes that are more convenient and economically viable to measure and identify heat-tolerant animals under farm conditions. Similarly, more advancements and cost reduction in data collection and genotyping are needed to develop genomic breeding values for heat tolerance. Genomic selection for heat tolerance in high-producing dairy cattle breeds such as Holsteins and Jerseys may be useful for the developed nations with more advanced data collection, efficient management systems, and genomic technologies. However, less developed countries with adapted local breeds may have better crossbreeding options between local stock and high producing exotic breeds. Nevertheless, selection for heat tolerance will improve the heat resilience of future animals and play an important role in supporting sustainable livestock production under changing climates.