Improvement of the frozen boar semen quality by docosahexaenoic acid (DHA) and L-cysteine supplementation
The aim of the present study was to investigate the effect of docosahexaenoic acid and L-cysteine supplementation on qualities of cryopreserved boar semen. A total of 30 ejaculates from 10 Yorkshire boars were included in the study. The semen was cryopreserved in lactose egg yolk base extender containing different concentrations of docosahexaenoic acid (fish oil) or/and L-cysteine : 0 mg and 0 mM (Control), 290 mg and 0 mM (Treatment I), 290 mg and 5 mM (Treatment II) and 290 mg and 10 mM (Treatment III). Post thawing semen qualities (sperm motility, motility patterns, sperm viability, acrosomal integrity, functional plasma membrane integrity and DNA damage) were assessed. The results show that sperm motility and sperm viability were significantly improved by supplementing of docosahexaenoic acid and/or L-cysteine, or their combination if compared to the control group (P < 0.05). The improvement of sperm parameters after supplementation of docosahexaenoic acid or/and L-cysteine, or their combination was more pronounced in the poor freezability sperm rather than at the good one. In poor freezability sperm, the supplementation of docosahexaenoic acid and/or 10 mmol/l L-cysteine resulted with higher sperm motility (34.7 vs. 22.3%, P < 0.001), sperm viability (45.0 vs. 28.1%, P < 0.05) and acrosomal integrity (46.9 vs. 36.2%, P < 0.05) if compared to the control. In conclusion, the supplementation of docosahexaenoic acid, alone or in combination with L-cysteine significantly enhanced the sperm motility, sperm viability and acrosomal integrity of boar sperm after cryopreservation.
Key words: Boar, docosahexaenoic acid, frozen semen, L-cysteine.