Abstract:
Preservation of semen is an important process to ensure that semen quality is sufficient for use in assisted reproductive technologies. This study evaluated the effectiveness of three different extenders to preserve bull semen stored under different conditions, as an alternative to frozen-thawed semen straws used for artificial insemination. Semen samples were collected from two Nguni bulls using an electro-ejaculator and transported to the laboratory at 37 °C for evaluation. Pooled semen was first aliquoted into three extenders namely Triladyl, Ham’s F10 and M199 at a dilution ratio of 1:4 (semen:extender), and then stored at controlled room temperature 24 °C. Secondly pooled semen was aliquoted into four groups of Ham’s F10 extender and diluted at a ratio of 1:4, then stored at 24 °C, 17 °C, 12 °C and 5 °C respectively. Sperm motility rates were analysed after 0, 24, 48 and 72 hours. Morphology, viability and sperm DNA fragmentation were analysed after 72 hours. The study was replicated four times and data was analysed by ANOVA. Triladyl had higher sperm viability rate and total motility rate for 72 hours (P<0.01). However, Ham’s F10 had higher progressive motility rate as compared to the other extenders. There was no significant difference (P<0.01), in the viability rate between Ham’s F10 and M199. No significant difference was also observed in total sperm abnormalities (absent tails, coiled tails and bent tails), except for reacted acrosomes (P>0.05), between the two Nguni bulls. Lower temperatures than 24 °C influenced sperm motility and viability in Ham’s F10. There was no significant difference in sperm DNA fragmentation rates (P<0.01), between all the four storage temperatures which indicated that temperature did not have an influence on sperm DNA fragmentation. In conclusion, bull semen can be preserved in Triladyl or Ham’s F10 and M199 culture media stored at 24 °C and stay alive for 72 hours. Triladyl proved to be the best suitable extender showing higher sperm viability and total motility rates as compared to Ham’s F10 and M199. Lower temperatures than 24 °C noticeably decreased sperm motility and viability in Ham’s F10 culture medium.
