Breeding pigs for improved heat tolerance through the integration of genomics and large-scale phenotyping

Why this research is being done

Heat stress negatively impacts the welfare and productive efficiency of pigs at different life stages. However, lactating sows are at a greater risk of deleterious heat-stress effects due to a substantial increase in litter and piglet sizes and, consequently, greater lactation demand and metabolic heat production. Genomic selection has been very effective in speeding up the rates of genetic progress for productive and reproductive traits, but the lack of indicators of heat tolerance in the selection indexes could unfavorably impact the heat stress response of modern sows. The development of a sustainable breeding program requires the identification of novel traits and genomic evaluation strategies to genetically select for improved heat tolerance.

Results

Over the past few years, Dr. Brito's team has investigated the genomic background of heat stress response in pigs, with a focus on lactating sows. With his team, they have developed the statistical genomic models and evaluated genetic parameters for numerous novel indicators of heat tolerance to be incorporated into pig breeding programs. They also identified the most representative environmental gradients to be included in the reaction norm models for genetically evaluating heat tolerance in both pigs and dairy cattle, identified various candidate genes and metabolic pathways influencing heat stress response, reported variance components (e.g., heritability and genetic correlations) for multiple indicators of heat tolerance, and developed genomic prediction models based on single-step genomic reaction models for genetically evaluating climatic resilience in pigs and dairy cattle.

Conclusions

We have provided a comprehensive description of the environmental-gradient variables and critical periods fitted in genomic evaluations of heat tolerance as well as the accuracy of genomic breeding values. We have described the genetic background of various indicators of heat tolerance and made recommendations for the implementation of genomic selection for improved heat tolerance in pigs.

Contact information

Luiz Brito britol@purdue.edu | 765-494-6088 | Google Scholar