Analysis of epididymal sperm from Korean native bull (Hanwoo) aged at 8 and 15 months before freezing and after thawing

The recovery of epididymal sperm in animals is considered as one of the important tools to preserve high value or endangered species. However, there are no appropriate castrating indicators such as months of age in bull, sperm morphology, and motility, particularly in young Korean native bull (Hanwoo). Therefore, this study aimed to investigate sperm number, morphology, and motility of sperm in the epididymis tail of young Hanwoo bulls at 8 and 15 months of age. After castration, epididymal tails were collected and minced with blades to recover sperm. In experiments 1 and 2, sperm number, morphology, and motility were examined. Total number of sperm and percentage of normal sperm from bulls at 8 months of age was lower than that of bulls at 15 months of age after collection (P