Advancements and challenges in in vitro reproductive technologies for the conservation of equine species

Assisted reproductive technologies (ARTs) have been proposed as a potential complementary strategy to other conservation efforts aimed at addressing the pressing challenges associated with managing endangered species. The Equidae family belongs to the order Perissodactyla and comprises various species, including domestic horses, donkeys, wild asses, zebras, and the Przewalski's horse, all of which belong to the genus Equus. Unfortunately, numerous subspecies of this order have become extinct in recent centuries, and many extant species are currently at risk of extinction. Recent decades have witnessed considerable progress in in vitro technologies, particularly in the domestic horse, including gamete collection and cryopreservation, as well as the successful production of embryos through in vitro fertilization techniques and cloning. Furthermore, some progress has been made in domestic donkeys and other wild equid species. However, for the majority of endangered species, effective ARTs protocols are not yet available. This review summarizes the main advances made in in vitro assisted reproductive technologies and genetic conservation efforts in equids and discuss the challenges and future prospects of these technologies in the context of wild equid conservation.