The cryoprotective effects of soybean lecithin on boar spermatozoa quality

Abstract

  Soybean lecithin has been attracted increasing attention and has been used to replace egg yolk in the cryopreservation of domestic animal semen. However, its effects on freezing boar spermatozoa have never been evaluated. In the present study, semen was collected from five Duroc boars and frozen-thawed in extender with different concentrations of soybean lecithin (3, 6, 9 and 12%) and 20% egg yolk. Semen parameters including sperm motion characteristics (the percentage of total motile sperm and motility), plasma membrane integrity and acrosome integrity were assessed with a computer-aided semen analysis (CASA) system, hypoosmotic swelling test (HOST) and fluorescein isothiocyanate-conjugated peanut agglutinin (FITC-PNA) method, respectively. The result best result was obtained for the extender supplemented with 6% soybean lecithin, with values of 59.7% for the percentage of total motile sperm (TM%), 44.3% for motility, 45.3% for plasma membrane integrity and 61.9% for acrosome integrity. TM%, motility, acrosome integrity and plasma membrane integrity in the extender containing 6% soybean lecithin were significantly higher than that of other concentrations of soybean lecithin and 20% egg yolk (P < 0.05). However, the percentages of TM, acrosome integrity and plasma membrane integrity decreased with the increasing concentration of soybean lecithin in extender. In summary, the effect of soybean lecithin on spermatozoa quality was superior and the effective concentration of soybean lecithin in extender was 6% (w/v). Soybean lecithin might replace egg yolk in extender in the cryopreservation of boar semen.   Key words:  Boar semen, cryopreservation, soybean lecithin, motility, acrosome integrity.