Effect of Conjugated Linoleic Acid on Boar Semen Quality After Long-term Refrigeration at 17°C

In this study, the effect of conjugated linoleic acid (10 trans, 12 cis) (CLA) on refrigerated boar sperm quality parameters up to 14 days at 17°C was assessed. Semen was extended in Androhep and divided into four treatments supplemented with CLA (25, 50, 100 and 200 μm) and control group, then kept for 2 h at 22°C. Afterwards an aliquot of each treatment was removed, and mitochondrial activity, viability, lipid membrane peroxidation (LPO) and stability of the sperm plasma membrane were assessed by flow cytometry. The remaining extended semen was maintained at 17°C until 336 h, repeating the same analysis every 48 h. Regarding percentage of live spermatozoa, no statistical differences were observed among treatments up to 96 h. After this time, viability decreased significantly (p < 0.05) for CLA concentrations of 100 and 200 μm. Despite these results, there was an individual response to CLA. Although in the control group, the boar A presented better results when compared with the other boars, especially at concentrations of 50 and 100 μm boar B showed significantly higher results (p < 0.05). Supplementation with CLA improved (p < 0.05) LPO, but not the mitochondrial membrane potential of sperm. The highest two CLA concentrations showed to be toxic for sperm as all results were lower than the observed for the control. In conclusion, CLA at 50 μm seems to be an efficient concentration for reducing the oxidative stress, decreasing LPO, maintaining viability, membrane stability and mitochondrial potential on refrigerated boar spermatozoa.