Effect of DHA-enriched hen egg yolk and cysteine on quality of cryopreserved boar semen

Abstract

The present study was performed to investigate the influence of extender used during equilibration (BTS® vs Modena™) and the effect of DHA-enriched hen egg yolks and/or cysteine supplementation in the freezing extender on the quality of cryopreserved boar semen. Seven ejaculates from seven Duroc boars and fifteen ejaculates from five Pietrain boars were used in experiments I and II, respectively. In experiment I, the semen sample was divided into 2 parts and each part was kept in BTS® or Modena™ at 15℃ for 120 min before cryopreservation. In experiment II, the semen sample was divided into 4 groups according to the composition of the freezing extender, i.e., normal hen egg yolk (group I), DHA-enriched hen egg yolk (group II), normal hen egg yolk with 5 mM of cysteine supplementation (group III) and DHA-enriched hen egg yolk with 5 mM of cysteine supplementation (group IV). The semen was cryopreserved by controlled rate freezer and was thawed at 50℃ for 12 sec. Progressive motility, sperm viability, intact acrosome and function of membrane integrity of the post-thawed semen were evaluated. The results revealed that the cryopreserved boar semen using Modena during equilibration yielded a better progressive motility and normal apical ridge than BTS (P<0.01). Experiment II demonstrated that the supplementation of cysteine in the freezing extender improved progressive motility (P<0.01). The post-thawed semen qualities were not significantly different between DHA-enriched hen egg yolks and normal hen egg yolk (P>0.05). The combination of cysteine supplementation and DHA-enriched hen egg yolk increased progressive motility and intact acrosome (P<0.01).