Association between Birth Weight and Testicular Development in Wagyu Calves

Reproductive traits in Wagyu cattle have been less extensively studied than meat quality characteristics. This study investigated the association between birth weight and testicular development in purebred Wagyu bulls. Thirty-four purebred Wagyu male calves from a single herd were monitored from birth until orchiectomy at approximately 200 days of age. At orchiectomy, the testes were weighed and measured. Histological samples were processed using hematoxylin and eosin staining to evaluate the diameter, height, and area of the germinal epithelium. Pearson’s correlation and linear regression models were used to assess relationships among birth weight, age, and histomorphometric parameters. A positive, though not statistically significant, correlation was identified between birth weight and germinal epithelium área (r = 0.312, P = 0.072). A significant sire effect was also observed for the assessed testicular traits. These findings provide limited evidence of an association between birth weight and testicular development; they do not establish a direct or causal relationship. Further studies are needed to clarify these relationships and their relevance to male fertility.