Selection for larger litter sizes has heightened sow milk production demands, increasing metabolic heat production and sensitivity to heat stress, particularly during hotter summer months. This can compromise both sow welfare and piglet growth. Genomic selection for enhanced heat tolerance offers a promising solution, but past approaches have often reduced productivity by focusing on lowering heat gain resulting in decreased metabolic activity. Therefore, the study aimed to biologically characterize a genomic selection model for improved heat stress tolerance based on the rate of body temperature increase as a function of ambient temperature. Under heat stress conditions, heat stress tolerant and heat stress sensitive lactating sows exhibited similar body temperatures. However, despite these body temperature similarities, heat stress tolerant sows maintained greater metabolic heat production overall throughout lactation. The ability to maintain greater metabolic activity without increasing body temperature response was likely driven by increased latent heat loss and more efficient behavioral thermoregulation in heat stress tolerant versus sensitive sows. These results highlight the potential for genomic selection strategies that enhance heat dissipation without compromising metabolic activity, offering a pathway to improve sow welfare, productivity, and piglet performance under heat stress conditions in the swine industry.

Read the full article in the Journal of Animal Science.