Department of Clinical Sciences, Division of Reproduction, Swedish University of Agricultural Sciences, Uppsala, Sweden.
Anim Reprod Sci. 2011 Aug;127(1-2):50-5. doi: 10.1016/j.anireprosci.2011.06.006. Epub 2011 Jul 18.
Gonadotropin-releasing hormone (GnRH) vaccine (Improvac(®)) is effective at diminishing boar taint by interfering with testis function. Early pre-pubertal vaccination at 10 and 14 weeks-of-age could be desirable if sufficient and sustained effects could be achieved. Crossbred male pigs (n=24) were randomly assigned to three groups each with eight individuals: an unvaccinated control group, one group vaccinated with Improvac(®) early at ages 10 and 14 weeks, and a third group vaccinated with Improvac at the standard ages of 16 and 20 weeks. The average age at slaughter was 25 weeks. At slaughter, reductions in testes weight and bulbourethral gland length of vaccinated pigs compared with controls were observed (P<0.001), accompanied by lowered testosterone concentrations in peripheral blood (P<0.001). The diameter of tubuli seminiferi was affected; being 18% smaller in standard and 38% smaller in early vaccinated males, compared with controls (P<0.01). Leydig cells in vaccinated pigs became pycnotic, and their number decreased in early vaccinated pigs. Spermatogenesis was disrupted, evidenced by spermatocyte loss among standard vaccinated pigs to severe spermatogenic arrest among early vaccinated pigs. This histological picture was reflected in the absence of epididymal spermatozoa in 5 of 8 early vaccinated pigs and a dramatic reduction in the remaining 3 early vaccinated pigs. Among standard vaccinated pigs, 5% of the spermatozoa were morphologically normal (>70% in controls, P<0.01). Early vaccination caused a more severe disruption of testicular structure and function than standard vaccination, thus providing an alternative for immunocastration of male pigs.
促性腺激素释放激素（GnRH）疫苗（Improvac(®)）通过干扰睾丸功能来有效减少公猪异味。如果能够达到足够和持续的效果，10 周和 14 周龄时的早期初情前免疫可能是可取的。杂交公猪（n=24）随机分为三组，每组 8 头：未免疫对照组、10 周和 14 周龄时用 Improvac(®)早期免疫的一组和 16 周和 20 周龄时用 Improvac 标准免疫的一组。平均屠宰年龄为 25 周。屠宰时，与对照组相比，免疫猪的睾丸重量和阴茎球腺长度降低（P<0.001），同时外周血中的睾酮浓度降低（P<0.001）。曲细精管的直径受到影响；与对照组相比，标准免疫和早期免疫雄性的直径分别小 18%和 38%（P<0.01）。免疫猪的睾丸间质细胞固缩，且数量减少，早期免疫猪的数量减少。精子发生受到干扰，表现为标准免疫猪的精母细胞丢失，以及早期免疫猪的严重精子发生停滞。这种组织学变化反映在 8 头早期免疫猪中有 5 头附睾中没有精子，其余 3 头早期免疫猪的精子数量显著减少。在标准免疫猪中，5%的精子形态正常（对照组中为>70%，P<0.01）。早期免疫导致睾丸结构和功能的破坏比标准免疫更为严重，因此为雄性猪的免疫去势提供了一种替代方法。
