Morphological defects of epididymal spermatozoa in male roe deer (Capreolus capreolus) during the reproductive season

The aim of this study was to analyse the morphology of the epididymal spermatozoa of male roe deer obtained postmortem at the beginning (May), peak (July/August) and the end (September) of the reproductive season. Spermatozoal abnormalities were divided into major (associated with impaired fertility) and minor (not associated with impaired fertility) defects. The highest percentage of abnormal spermatozoa was observed in May (17.78 ± 1.88%), with a much higher proportion of major (12.35 ± 1.11%) than minor defects (5.43 ± 1.59%) being observed. The percentage of abnormal spermatozoa was lowest during the peak of the reproductive season (4.97 ± 1.13%), with the proportion of major (2.68 ± 0.78%) and minor defects (2.28 ± 0.45%) being comparable during this period. The percentage of abnormal spermatozoa increased again in September (11.05 ± 1.60%), with the major defects (6.15 ± 1.04%) slightly surpassing the minor defects (4.90 ± 0.77%); however, total abnormalities still remained lower than those found in May. These differences were statistically significant, with the exception of the difference in minor defects between the pre-rut and post-rut periods. These results indicate that the best period to collect epididymal spermatozoa from roe deer postmortem is the peak of the reproductive season (July/August); however, they can also be recovered at the end of the reproductive season (September), as the percentage of major defects is relatively low at this time. This study provides the basis for further research to determine optimal methods for the storage and cryopreservation of epididymal spermatozoa in this species