EFFECT OF SUBSTITUTION EGG YOLK WITH DIFFERENT LEVELS OF SOYBEAN LECITHIN IN TRIS-BASED EXTENDER ON FREEZING AND FERTILIZING CAPACITY OF HOLSTEIN BULL SEMEN

Abstract

Soy bean lecithin has been attracted increasing attention and has been used to substitution egg yolk in the semen extender. Aim of the currentresearch articlewas to study the impact of substitutionof egg yolk with soybean-lecithin in tris-extender on freezability and fertilizing capacity of Holstein sperm in post-thawed semen. Semen from five Holstein bulls was frozen in tris-citric acid extender containing 15% egg yolk (EY, control) or 0.25, 0.5 and 0.75% soybean-lecithin (SBL). Percentages of motility, viability, plasma membrane integrity and intact acrosome spermatozoa were assessed in diluted, equilibrated and thawed semen. Results showed that0.5% SBL-extender had positive (P<0.05) effect on percentages of motility, livability, plasma membrane integrity and intact acrosome of sperm cellsafter dilution, equilibration and thawing.In post-thawed semen, the highest (P<0.05) spermrecovery rate of motility,livability, plasma membrane integrity and intact acrosome was obtained for 0.5% SBL-extender compared to other extenders.The highest conception rate (68.6%) of Holstein cows was obtained following insemination with semen extended with 0.5% SBL compared with other extenders (48&56%). In conclusion, egg yolk could be substituted by soybean-lecithin in tris-based extender at a level of 0.5% to improve fertilizing capacity of cryopreserved Holstein semen.