Substitution of egg yolk with different concentrations of soybean lecithin in tris-based extender during bulls' semen preservability

Abstract

To investigate the effect of various concentrations of soybean lecithin as an alternative for egg yolk in bull semen extender on post-chilling and post-thaw sperm quality characteristics. Semen ejaculates were collected from three mature bulls' once/week for 5 weeks. After initial evaluation the approved ejaculates were pooled and extended gradually 1:7 with tris-citrate-fructose egg yolk extender (control) and tris-citrate-fructose (TCF) + different concentration of soybean lecithin (0.5%, 1.0%, 1.5%, 2.0%, 2.5%, 3.0%, 3.5% and 4.0%) to ensure 60 million motile spermatozoa/mL, and then proceeded an adopted international cryopreservation protocol. Frozen straws were thawed at 37 °C for 30 s. The parameters studied were sperm motility, viability, abnormality, membrane integrity and normal intact acrosome percentages in chilled and frozen-thawed semen. The substitution of egg yolk into TCF with 1% soya lecithin significantly (P < 0.000 1) ameliorated the maintenance of semen characters motility (86.67% ± 0.80%), life (87.60% ± 0.88%), and membrane integrity (82.47% ± 0.94%), meanwhile it had significantly (P < 0.000 1) reduced the abnormality (13.20% ± 0.60%) of spermatozoa to its least value compared to some other concentrations in use. Moreover, the addition of 1.5% of soya lecithin to TCF had maintained the semen characteristics compared to the control tris-citrate-fructose egg yolk. The significantly higher mean values of post-thawing sperm motility % were observed in 1% soybean lecithin (56.00% ± 1.00%) as compared to the control (41.00% ± 1.00%). 1–1.5% soya lecithin can effectively alternate egg yolk as cryoprotective additives for cryopreservation extender, without any detrimental effects on post-chilling and post-thaw semen quality in cattle bull.