Toxicological implications of climate change for reproductive function in livestock

Climate change-driven heat stress is an emerging toxicological stressor that disrupts thermoregulation and endocrine function, impairing livestock fertility across the reproductive lifespan. This review aims to synthesize mechanistic evidence linking heat stress to female reproductive dysfunction in cattle, pigs, and poultry. Growing evidence indicates that climate change-associated heat stress compromises female reproduction in cattle, pigs, and poultry. In cattle, chronic heat stress perturbs the hypothalamic–pituitary–gonadal and stress axes, induces oxidative and mitochondrial damage in gametes and embryos, and disrupts uterine signaling, thereby impairing implantation and maternal recognition of pregnancy. In pigs, impaired heat dissipation, negative energy balance, and uterine and placental injury converge to reduce fertility and compromise pregnancy maintenance. In poultry, heat stress alters neuroendocrine and intestinal functions and diverts energy away from reproduction, leading to sustained declines in laying performance and egg quality. These findings highlight heat stress as a multidimensional reproductive toxicant in livestock and the need to evaluate its cumulative impact on fertility under climate warming.