Immunization against inhibin improves in vivo and in vitro embryo production

The multiple ovulation and embryo transfer (MOET) technique has become an important breeding method in modern animal selection programs and a reproductive technique that can bypass ovarian dysfunction caused by heat stress to maintain reproductive performances in dairy cows. However, oocyte and embryo development often suffer from defects following repeated superovulation protocols. This phenomenon might be attributed to high levels of circulating inhibin, which is secreted by the supra-normal numbers of developing follicles during the process of superovulation. Through inhibin's negative impact on ovarian follicle development, high concentrations of inhibin might reduce oocyte quality and embryo developmental competence. Neutralizing endogenous inhibin bioactivities by active or passive immunizations against inhibin has been demonstrated to stimulate extra follicle development and induce multiple ovulations in both rodents and ruminants. Combined with conventional superovulatory protocols, immunization against inhibin further enhances follicle development and embryo yield. Furthermore, immunization against inhibin not only enhanced embryo quantity but also embryo quality in studies conducted in cows, sheep and water buffaloes. Similar beneficial effects on enhancing embryo development quality have been demonstrated in in vitro studies, where treatment with inhibin α subunit antibody enhances oocyte maturation and development of IVF or parthenogenically activated embryos. Thus, immunization against inhibin in combination with a conventional superovulation protocol can become a new technique to improve embryo production efficiency in vivo, as well as to develop a new oocyte IVM/IVF technique that can improve embryo IVP production efficiency.