In practice, two injections of gonadotropin‐releasing hormone (GnRH) vaccine are recommended for pig immunocastration for effective outcomes. The present study aimed to investigate the expressions of cytochrome P450 aromatase (P450_arom) and anti‐Müllerian hormone (AMH) in testes, testicular length and testicular histomorphometry of the fattening pigs receiving the first injection of GnRH vaccine 6 weeks earlier than the standard protocol. Based on vaccination protocol, 24 pigs were equally divided into three groups: T1 was vaccinated at 15 and 19 weeks of age, T2 received vaccine at 9 and 19 weeks of age and C remained intact. P450_arom and AMH expressions were analysed using immunohistochemistry and Western blot. The results revealed that testicular length was highest in C pigs, but not different between T1 and T2 groups (6.5 ± 0.2 versus 6.9 ± 0.3 cm, p = .538). Histomorphometry demonstrated that the height of spermatogenic epithelia, the diameter of seminiferous tubules and the number of seminiferous tubules between T1 and T2 groups were not different (p > .05). For P450_arom, immunohistochemistry revealed that H‐score of C group was significantly higher than that of both T1 and T2 groups. Western blot analysis showed that C group possessed the densest protein band. Moreover, H‐score between T1 and T2 groups was not significantly different. Protein band intensity between both groups was not apparently different. As for AMH, C pigs had significantly lower H‐score than both T1 and T2 pigs. Furthermore, T2 pigs possessed significantly higher H‐score than T1 pigs. Western blot analysis showed that the most intense protein band was found in T2 group. In summary, GnRH vaccine affected testicular development and functions. The first injection could be performed either at 9 or 15 weeks of age since both protocols contributed to comparable results in aspect of testicular length, histomorphometry and expressions of P450_arom and AMH.

中文翻译：

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免疫阉割首次接种时间对育肥猪睾丸细胞色素P450芳香化酶和抗苗勒管激素的表达的影响

在实践中，推荐两次注射促性腺激素释放激素 (GnRH) 疫苗进行猪免疫阉割以获得有效结果。本研究旨在调查比标准方案提前 6 周接受首次注射 GnRH 疫苗的育肥猪的睾丸、睾丸长度和睾丸组织形态计量学中细胞色素 P450 芳香酶 (P450 _arom ) 和抗苗勒管激素 (AMH)的表达。. 根据疫苗接种方案，将 24 头猪平均分为三组：T1 在 15 和 19 周龄时接种，T2 在 9 和 19 周龄时接种疫苗，C 保持完整。P450_芳烃使用免疫组织化学和蛋白质印迹分析 AMH 表达。结果显示，C 猪的睾丸长度最高，但在 T1 和 T2 组之间没有差异（6.5 ± 0.2 对 6.9 ± 0.3 cm，p  = .538）。组织形态计量学显示，T1组和T2组生精上皮高度、曲细精管直径和曲细精管数量无差异（p  >0.05）。对于 P450_芳香族, 免疫组化显示 C 组的 H-score 显着高于 T1 和 T2 组。蛋白质印迹分析显示C组具有最密集的蛋白质条带。此外，T1 和 T2 组之间的 H 评分没有显着差异。两组之间的蛋白质条带强度没有明显差异。至于 AMH，C 猪的 H 分数显着低于 T1 和 T2 猪。此外，T2 猪的 H 分数显着高于 T1 猪。蛋白质印迹分析显示，在T2组中发现了最强烈的蛋白质条带。总之，GnRH疫苗影响睾丸发育和功能。第一次注射可以在 9 周或 15 周大时进行，因为两种方案都有助于在睾丸长度、组织形态测量和 P450 表达方面产生可比的结果_芳香族和AMH。