Return of testicular function after vaccination of boars against GnRH: consequences on testes histology.

Traditionally, male pigs are surgically castrated without anaesthesia to avoid later occurrence of the sex odour of androstenone in the carcass. Active immunization against gonadotropin-releasing hormone (GnRH) is a painless alternative which inhibits LH and thus steroidogenesis in the Leydig cells. In a preceding study we clarified the return of Leydig cell function after the last dose of antigen by measuring hormones, and found a considerable variation (10 to 24 weeks) till return of their function (testosterone 0.

Individual return to Leydig cell function after GnRH-immunization of boars.

Immunization of boars against GnRH inhibits synthesis of testicular anabolic steroids and the sex odour androstenone. Time between second vaccination and return of Leydig cell function is unknown. Six catheterized boars received the second dose (Improvac) at 26 weeks of age (day 0).