Heat and chemical stressors: Independent and interactive impacts on the pig ovary

Seasonal infertility as a phenotypic consequence of heat stress has been recognized in production animals for decades and more recently in women. Systemic impacts of heat stress include compromised intestinal integrity, and elevated prolactin and insulin. These effects alone can compromise female fertility. There are also ovarian endocrine changes and molecular sequelae that have been identified. This review summarizes the current literature with a focus on the pig as a model. In addition to direct thermal effects on fecundity, the influence of heat on the ovarian capacity to respond to chemical exposures that are also fertotoxic is discussed. The toxicants of focus are zearalenone and perfluorooctanoic acid, both of which are risks to porcine fertility. Reduced fertility is detrimental to animal welfare, economic sustainability and food security and identification of mechanisms is requisite for development of mitigation strategies.