Suppression of reproductive function in juvenile rams by a slow-release gonadotropin-releasing hormone implant

BACKGROUND: Regarding animal welfare and reversible suppression of reproduction the need for alternatives to surgical castration, like slow-release gonadotropin-releasing hormone (GnRH) implants, is increasing. AIM: In this study, we evaluated whether the onset of puberty can be suppressed by implantation of a slow-release GnRH implant (4.7 mg deslorelin) in juvenile rams. METHODS: Seven juvenile rams (3–5.5 months) were treated with the GnRH analog deslorelin to analyze the effects on testicular development, sonographic findings of testicular tissue, testosterone concentration in the blood, spermatogenesis, and sperm parameters from the epididymis after castration. Seven rams of the same age without an implant served as controls. RESULTS: Follow-up examinations were conducted over 5 months, after which four rams per group were castrated. No significant group differences were found in the andrological parameters on the group level, but testicular development was suppressed in three rams in the treated group. Histological examination revealed spermatogenesis in the testicular tissue in three of four animals treated with a GnRH analog. CONCLUSION: The onset of puberty in juvenile rams cannot be reliably suppressed by using the slow-release GnRH implant Suprelorin®.