O-11: Immunoneutralization of Inhibin Alpha Subunit as A Tool for Improving Farm Animal Fertility

Background: The objectives of a series of studies undertaken was to improve farm animal reproductive efficiency in terms of embryo production efficiency, conception rate and litter size by immunoneutralization of inhibin in conjunction with other conventional reproductive techniques. Materials and Methods: A recombinant porcine inhibin alpha-subunit mature peptide was produced by mass scale and used as the antigen to immunize animals coupled with either standard superovulatory or oestrus synchronization protocols. Super-ovulation tests were carried out in both Holstein dairy heifers and swamp water buffaloes in single or 3 consecutive super-ovulations. Anti-inhibin or anti-follistatin antibodies were supplemented into oocyte IVM media in studies to improve in vitro embryo production efficiency. Oestrus synchronization was carried out in both water buffaloes and repeat breeder Holstein dairy cows. Concentrations of reproductive hormones were also monitored throughout super-ovulation or oestrus synchronization procedures. Results: Immunization against inhibin improved blood concentrations of oestradiol during the follicular phase and progesterone during the luteal phase, stimulated expression of oestrous behavior, improved superovulatory response, and most importantly enhanced embryo quantity and also quality in both Holstein heifers and water buffalo cows. Immunization against inhibin also increased plasma concentrations of FSH and activin, and also the ratio of activin to follistatin during the follicular phase. In the in vitro study supplementation of anti-inhibin antibody into the oocyte IVM culture medium improved oocyte maturation rate, cleavage rate, but not blastocyst rate. However, supplementation of anti-follistatin into the IVM medium doubled the blastocyst rate as well as increasing oocyte maturation rate and cleavage. Immunization against inhibin, when combined with the oestrus synchronization protocol, also substantially increased ovulation rate and also conception rate following artificial insemination in water buffalo cows plus conception rate in repeat breeder Holstein dairy cows. Conclusion: 1. Immunization against inhibin, through neutralizing bio-activity of inhibin, creating a hormonal effect of higher activin to follistian or activin to inhibin ratio result in improved oocyte maturational and embryo developmental qualities and enhanced embryo quantity but also quality after super-ovulation treatment. 2. Immunization against inhibin, by bringing together the above 3 prerequisites of establishing pregnancy, i.e. higher secretion of oestraiol in follicular phase, higher progesterone secretion in luteal phase, and enhanced oocyte and embryo qualities results in improved ovulation rate and conception rates in animals after oestrus synchronization treatment.