Global oxidative stress estimation using chemiluminescence for evaluating semen quality in boars with different fertility indices.

Oxidative stress (OS) in ejaculates is a key indicator of semen quality. The aim was to estimate global OS using chemiluminescence and malondialdehyde (MDA) based methods in fresh (0h) and extended preserved (48h and 96h) semen of boars with different fertility indices. Based on the boar fertility index (BFI >10, ∼7-8 and <6), boars (n = 6) with three fertility (high, medium and low) levels were used to collect semen (n = 72). Routine semen evaluation tests along with OS estimation by MDA and chemiluminescence methods were done in fresh (0h) and extended semen at 48, 96 h of preservation. In results, routine assessment tests were not significantly (p > 0.05) reliable in determining fertility according to the corresponding BFI. Only low (BFI < 6) fertile boar's extended ejaculates at only 96 h of preservation could be distinguished using MDA-based OS estimation (p < 0.05). There was a significant (p < 0.05) difference between the OS levels measured by chemiluminescence in fresh (5.81 ± 0.16 vs 7.36 ± 0.15 vs 9.05 ± 0.24 RLU/s) and extended ejaculates (48h, 96h) of high (BFI > 10), medium (BFI∼7-8) and low (BFI < 6) fertile group boars. A weak (r = -0.12) to moderately (r = -0.29) negative correlation was observed between routine semen quality assessment and OS estimated by chemiluminescence. However, the initial capital cost of the chemiluminometer was the major limitation apart from the study over larger population and samples. In conclusion, the chemiluminescence method was a more accurate method than MDA to assess global OS level in the semen and can be used to predict the boar fertility grades.