Abstract: To compare the differences in testicular development and semen quality among Neijiang pigs, Yorkshire pigs, and their reciprocal crossbred boars, this study systematically analyzed the effects of breed and month of semen collection on semen quality, and compared testicular development indices across different breeds. The results showed that significant differences in both semen quality and testicular development among breeds (P＜0.05). Neijiang boars exhibited low sperm production but a low abnormality rate, while Yorkshire boars showed a high effective sperm count but a high abnormality rate. The reciprocal crossbred boars combined the advantages of both parental breeds, demonstrating significantly higher effective sperm count, ejaculate volume, and sperm concentration than Neijiang boars (P＜0.05), and a significantly lower abnormality rate than Yorkshire boars(P＜0.05). Testicular development indices of Yorkshire and reciprocal crossbred boars were significantly higher than those of Neijiang boars (P＜0.05). As the month of semen collection increased, the reciprocal crossbred boars showed comprehensive improvements in all semen quality parameters, indicating full reproductive development; Neijiang boars only showed increase in effective sperm count and ejaculate volume, while Yorkshire boars exhibited stable semen quality. The effect of collection month on semen quality was breed specific: effective sperm count increased with age in Neijiang and reciprocal crossbred boars, whereas in Yorkshire boars it did not significantly increase until 19～24 months of age. In conclusion, the reciprocal crossbred boars derived from Neijiang and Yorkshire pigs showed stable reproductive development, clear hybrid vigor, and superior semen quality.

Key words: Neijiang pig, Yorkshire pig, reciprocal cross, semen quality, breed difference