Influence of some cryoprotectants in comparing with different glycerol levels on sperm viability during freezing process of goat semen [electronic resource].

Includes reference.

A total of 160 good quality ejaculates were collected for freezing from 10 mature Zaraiby bucks (28.4±0.9 kg LBW and 25-35 mo old) in Sakha Research station during JUly-August period (twice/week for 8 wk) to determine the optimal level of, glycerol alone (1 to 7%. 1st experiment) and comparing the optimal level of glycerol with its combination with dimethyl sulfoxide (OMSO) and different levels (1. 3 and 5%) of et~lene glycol (EG), ethanol and methanol as cryoprotectants in Tris-based extender (2 experiment). and the effect of the cryoprotectauts on sperm motility percentage (SMP) and recovery rate (RR%) at different freezing process stages (dilution, equilibrium and thawing). Results of the 1" experiment show that SMP in post-diluted and post-equilibrated semen was not affected significantly by glycerol (GL) level ranging between 79-81%. Loss in SMP between dilution and equilibrium ranged between 1-3% for all GL levels. being the lowest for 7% level and the highest for 5% level. Post-equilibrated RR of sperm motility ranged from 96.3 for 5% level to 98.8% for 4 and 7% levels. SMP showed gradual Increase (P<0.05) from 20 to 48% by increasing GL level from 1 to 6%. Increasing GL level to 7% led to insignificant reduction in SMP (46%). Glycerol at 6% level showed the lowest (P<005) SMP loss (30%) and highest RR (61.5%) of sperm motility in post-thawed semen. The highest RR (72%) was obtained in 2 h post-thawed semen with 5% GL level, but did not differ significantly from that diluted with 6 and 7% levels. No viable spermatozoa were found 2 h post-thawing in semen diluted with extenders containing low glycerol levels (1 and 2%). Results of the 2" experiment show that semen diluted with 6% GL showed the best results based on SMP and RR in post-diluted and post-equilibrated semen as compared to the other cryoprotectant levels. Level of 3% EG showed similar results to 6% GL level, while all methanol levels reflected the poorest results as compared to the other levels of cryoprotectants. In post-thawed semen, SMP and RR were the highest (P<0.05) and loss in SMP was the lowest (P<0.05) for 6% GL (47%). followed by 3% GL+3% OMSO and 6% OMS (39 and 34%. respectively). Non-viable spermatozoa were observed in 2 h post-thawed semen diluted with all levels of EG. ethanol or methanol. However, SMP in 2 h post-thawed semen was affected significantly (P<0.05) by diluents containing GL. OMSO or their combination. being 33, 16 and 24%, respectively. Similar trend was obtained for sperm recovery rate in 2 h post-thawed semen, being 70.0, 55.9 and 615%, respectively. The current study indicated that adding glycerol to Tris-based extender at level of 6% for cryopreservation of Zaraiby goat semen frozen in pellets form yielded the highest sperm motility in post-thawed semen.

Summary in Arabic.

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