Abstract:
This study was conducted to investigate the effectof different concentrations of soybean lecithin extenders on motility of chilled and frozen sperms in Nubian bucks. A total of fifty nine ejaculates were collected from six fertile bucks once a week during nine consecutive weeks using artificial vagina. Initial evaluation of fresh semen revealed that the normal colour was creamy to milky,consistency was fairly uniform and thin (4.70±0.5).The average of total volume was1.03±0.3 ml. The mass motion of sperms was 4.64 ±0.6 while the individual motility was 93.48±3.1%. The percentages of viability (life sperms) and dead sperms were 92.73±4.0 % and 7.27±4.1%, respectively. The correlation between the colour and consistency; dead sperms and colour and between life and dead sperms were significant (P ≤ 0.05). After initial evaluation of ejaculates, 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 between two concentrations of TCSL and TCEY at temperature 5 ºC for 1hour (very good motile: 80-100%) and 4hour (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 (-196 ºC) for 30 days were significantly higher than those containing TCSL 4%(p<0.05)However, there were no significant differences between motility rates of frozen semen diluted with TCSL and TCEY. It is concluded thatsoybean lecithin 3%provided the best motility of frozen-stored spermatozoa than the soybean lecithin 4% and egg yolk.
