Short Communication IXth International Conference on Boar Semen Preservation 2019

Replacing egg yolk with lecithin in the semen extender compromises the quality of frozen-thawed boar sperm (#1.3)

Pachara Pearodwong 1 2 , Junpen Suwimonteerabutr 1 2 , Janyaporn Rungruangsak 3 , Padet Tummaruk 1 2
  1. Department of Obstetrics, Gynaecology and Reproduction, Faculty of Veterinary science, Chulalongkorn University, Bangkok, 1330, Thailand
  2. Swine Reproduction Research Unit, Faculty of Veterinary Science, Chulalongkorn University, Bangkok, 1330, Thailand
  3. Embryo Transfer Technology and Germplasm Research Center, Pakchong, Nakhonratchasima, 30130, Thailand

Lecithin or phosphatidylcholine is one of the phospholipids extracted from soybeans. Lecithin as a substitution for egg yolk in semen extenders has been investigated during the past decade in many species, including bucks, bulls, tom cats, male dogs and boars. Nevertheless, the use of lecithin in the cryopreserved boar semen extender is still rare. The aim of the present study was to determine the effect of replacing egg yolk with lecithin in the extender on the quality of frozen-thawed boar sperm. A total of 15 ejaculates from 6 proven Duroc boars (2-4 years old) were included in the experiment. Each ejaculate was equally aliquoted for cryopreservation in egg yolk-based (n=15) and lecithin-based (n=15) extenders. Three extenders (I, II and III) were used. Extender I was a commercial boar semen extender. Extender II was classified into 2 groups: egg yolk-based (80 ml of 11.0% lactose solution and 20 ml of egg yolk) and lecithin-based (80 ml 11.0% lactose solution, 6.0 g of lecithin and 20 ml distilled water). Extender III contained extender II plus 10.0% glycerol and 1.5% Equex STM Paste. The post-thawed total motility of sperm was evaluated by CASA. Sperm viability, acrosome integrity, mitochondrial activity and plasma membrane integrity were evaluated by SYBR14/Ethidiumhomodimer-1 staining, fluorescein isothiocyanate-labelled peanut agglutinin (FITC-PNA) staining, JC-1 staining and the hypo-osmotic swelling test, respectively. All measured sperm parameters (expressed as means ± sem) were better in the egg yolk-based than in the lecithin-based extenders: 37.8 ± 3.6 vs 27.8 ± 3.6 (P < 0.001), 44.0±2.1 vs 32.5±2.1 (P < 0.001), 31.7±1.3 vs 23.3±1.3 (P < 0.001), 49.3±3.1 vs 35.0±3.1 (P = 0.003) and 60.2±2.9 vs 52.5±2.9 (P = 0.047) for total motility, viability, plasma membrane integrity, mitochondrial activity and acrosome integrity of sperm, respectively. It can be concluded that replacement of egg yolk by lecithin in the extender for cryopreserved boar semen compromised the quality of frozen-thaw boar sperm. Thus, the use of lecithin at the present concentration (6.0%) is not recommended.