Effect of soybean lecithin-based semen extender on motility of the chilled and frozensemen in Nubian bucks

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.