3.3. Inhibin Immunization

Inhibin (INH) is a heterodimeric glycoprotein (31–34 KDa) found as two isotopes i.e., INH A (α-βA) and INH B (α-βB), that share a common α subunit, differ in the β subunit, and play important roles in the hypothalamus pituitary gonadal (HPG) axis [90,91,92]. INH is a negative feedback regulator of FSH [93]. INH is secreted by Sertoli cells in male testes and granulosa cells of ovarian follicles in females [94]. In males, FSH directly acts on Sertoli cells that nourish germ cells, ultimately negatively effecting reproductive efficiency.

INH immunization is an effective tool for improving reproductive performance in various commercial animals and bird species. In Yangzhou ganders, immunization against the INH α-subunit improved testicular weight and Sertoli cell development but lowered T concentration [95]. Plasma T concentrations are not standard for semen quality in goose flock management [22]. In Japanese quail, INH immunization expedited puberty and elevated hen-day egg production [96]. In Partridge Shank hen, the INH vaccine enhanced the production of antibodies against INH, follicular development, and egg production. In hens from juvenile state to sexual maturity, INH immunization upgraded rate of ovulation and follicular development without increasing FSH [97]. Immunization against the INH α subunit promoted testicular development in developing cockerels [98] without effecting FSH. However, INH immunization did not significantly enhance egg production in turkey hens [99]. α-INH immunization improved daily sperm production in rams [100].