Abstract:
This study was conducted to investigate the effect of different concentrations of soybean lecithin extenders on motility of sperms in the chilled and frozen semen of Nubian bucks. A total of 59 ejaculates were collected from 6 fertile bucks once a week during 9 weeks interval using artificial vagina. After initial evaluation of ejaculates, the semen samples were divided into three equal groups and diluted at 1:5 (semen: extender) using extenders containing 2% egg yolk with tris –citric acid (TCEY, control group, n= 59), 3% soybean lecithin with tris-citric acid (TCSL 3%, n=59) and 4% soybean lecithin with tris-citric acid (TCSL 4%, n=59).The motility rates of spermatozoa after equilibration period at 5ºC for one and 4 hours; and after freezing at -196 ºC for 30 days were recorded.The results indicated that there were no significant differences in motility rates among the deferent concentrations of TCSL and TCEY at temperature 5 ºC for 1 (very good motile: 80-100%) and 4 (good motile: 60-79%) hours. Overall mean of sperm motility rates was lower after cooling for 4 hours than 1 hour. The motility values of post-thawed semen containing TCSL 3% after cryopreservation at -196 ºC for 30 days were significantly higher (66.36 ± 10.3 %) than those containing TCSL 4% (60.34 ±11.9 %) (p<0.05). However, there were no significant differences between motility rates of frozen semen diluted with TCSL and TCEY. It could be concluded that soybean lecithin 3% provided the best motility of frozen-stored spermatozoa than soybean lecithin 4% and egg yolk.
