The activity of paraoxonase type 1 ( PON ‐1) in boar seminal plasma and its relationship with sperm quality, functionality, and in vivo fertility

Summary Paraoxonase 1 ( PON ‐1) is a hydrolytic enzyme present in body fluids, capable of protecting cells against oxidative stress. The hypothesis was hereby to test that PON ‐1, present in seminal plasma ( SP ), acts protecting boar spermatozoa when showing a reasonable high activity in the ejaculate. SP ‐ PON ‐1 activity differed ( p  <   0.001) among boars (from 0.10 to 0.29  IU / mL ). Intra‐boar variability was also observed ( p  <   0.05), but only in two of the 15 boars. SP ‐ PON ‐1 activity differed among ejaculate portions, showing the spermatozoa‐peak portion of spermatozoa‐rich ejaculate fraction the highest levels (0.35 ± 0.03  IU / mL , ranging from 0.12 to 0.69) and the post‐sperm ejaculate fraction the lowest levels (0.12 ± 0.01  IU / mL , ranging from 0.03 to 0.21). SP ‐ PON ‐1 activity was positively correlated with the percentage of spermatozoa with rapid and progressive movement ( p  <   0.01) and negatively correlated with the generation of intracellular reactive oxygen species ( p  <   0.01) in semen samples after 72 h of liquid storage. SP ‐ PON ‐1 activity was highest ( p  <   0.01) in boars with highest farrowing rates. In conclusion, SP ‐ PON ‐1 activity differed among boars and ejaculate fractions/portions. SP ‐ PON ‐1 activity was positively correlated with sperm quality and functionality of liquid‐stored semen samples and it evidenced a positive association with in vivo fertility.