The sperm DNA damage after cryopreservation of boar semen in relation to post-thawed semen qualities, antioxidant supplementation and boars effects

The objectives of the present study were to evaluate the damage of DNA of the frozen-thawed (FT) boar spermatozoa and to investigate the effect of various concentrations of L-cysteine supplementation on the sperm DNA damage. A total of 104 cryopreserved semen samples from twenty-six ejaculates of 16 proven boars were analyzed. Of these samples, each semen sample contained a different concentration of L-cysteine i.e., 0 (n=41), 5 (n=41), 10 (n=11) and 15 (n=11) mM. All of the semen samples were cryopreserved by controlled-rate freezer. The semen was thawed at 50°C for 12 sec and the damage to the sperm DNA was determined using acridine orange (AO) staining. The results revealed that, on average, the DNA damage was observed in 0.5% of the FT boar spermatozoa. DNA damage varied among the boars from 0.0% to 4.0%. The levels of DNA damage were 0.6%, 0.4%, 0.5% and 0.9% in the extenders supplemented with 0, 5, 10 and 15 mM of L-cysteine, respectively (p>0.05). In conclusion, the DNA damage of the FT boar spermatozoa was relatively low. No adverse effect of L-cysteine supplementation up to 10 mM on the damage of the sperm DNA was found. Boar characteristic is the most important factor affecting the damage of the sperm DNA.