Heat stress is problematic for pigs raised in tropical environments. The animal is large and has proportionally high body heat, and subcutaneous fat thickness reduces the animal's ability to thermoregulate. It is not clear how stress affects pig litter size. For this reason, we performed a meta-analysis of the effect of heat stress on pig litter size. We reviewed behavioral, endocrine, and cellular data and the signaling pathways involved in heat stress. We found that heat stress did not affect litter size or the body weight of offspring. However, heat stress was found to decrease litter body weight gain due to reductions in sow milk production. For this reason, artificial feeding of piglets may be appropriate.
Keywords: Heat stress; Litter; Meta-analysis; Pig.