Interpretive Summary: Evaluation of sow thermal preference across three stages of reproduction

By Anne Zinn

Heat stress can cause infertility in sows, increased wean-to-estrus interval, reduced farrowing rate, and reduced litter size, and litter weight. Over the past 30 years, the metabolic heat production of modern pigs has increased by an average of 16%, which means it is likely that temperature recommendations require updating to meet the needs of modern pigs. A paper recently published in the Journal of Animal Science evaluated whether different reproductive stages of sows altered thermal preference and if current recommendations required updating. It was hypothesized that the reproductive stage would alter thermal preference in sows. This study is the first to look at temperature preference differences based on the reproductive stage of sows.

Overall, the results demonstrated that sow thermal preferences were within the lower half of the current recommended range (10 to 25 °C) and suggested that temperatures at the higher end of the recommended range could be uncomfortable to sows and that the thermal comfort zone of sows may be narrower than recommendations indicate. Specifically, late-gestation sows prefer a temperature range of 12.6 to 15.6  °C and may have a cooler upper critical limit than what is currently recommended. These results suggest that sows might experience heat stress at cooler temperatures than expected based on the stage of reproduction and require behavioral and physiological adjustments sooner to mitigate the negative effects of heat stress. Based on these results, individual sows should be housed in temperatures between 12.6 and 16.4 °C to provide their thermal comfort zone and could optimize production and improve the overall well-being. The temperature preferences demonstrate that further research is required to produce accurate guidelines on preferred temperature ranges.

The full paper can be found on the Journal of Animal Science webpage.