Climate change presents new problems for agriculture production such as heat stress. Heat stress causes a large economic impact in addition to animal welfare concerns across livestock industries. Heat stress solutions include management changes as well as genetic selection to improve heat tolerance. We investigated the existence of genotype-by-environment interactions based on heat stress for beef cattle and swine. Beef cattle data included 82,669 weaning and 69,040 yearling weights, and swine data included 207,233 170-d weights on purebreds and 228,191 hot carcass weights on crossbreds. An index of temperature and humidity characterized heat stress, and the cumulative heat stress after a threshold (heat load) was modelled as a reaction norm. Purebred swine had no genotype-by-environment interaction for heat stress because of the quality of the production environment, but genetic differences existed in the crossbred animals for heat tolerance. A similar interaction occurred for the direct component of cattle growth. Strong genetic correlations were present for the maternal component of cattle growth, which was unexpected because a genotype-by-environment interaction exists for milk production in dairy cattle. Improving thermal tolerance would be a step toward alleviating animal welfare concerns associated with heat stress. Global meat animal production would benefit from selection tools for improving heat tolerance and for developing a more resilient food supply. As climate variability increases, research will need to shift from assessing current conditions to incorporating the increasing variability of weather conditions. Keywords: genotype-by-environment interaction, heat stress

Heather Bradford, Breno Fragomeni, Shogo Tsuruta, Keith J. Bertrand, Kent Gray, Yijian Huang, Daniela Lourenco, Ignacy Misztal

Proceedings of the World Congress on Genetics Applied to Livestock Production, Volume Challenges - Genotype by Environment Interactions, , 158, 2018
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