Superoxide dismutase (SOD) is a major antioxidant enzyme in boar seminal plasma (SP). This study evaluated how SP-SOD affected sperm attributes when semen of boars of various breeds, included in commercial artificial insemination (Al)-programs, was extended and liquid-stored at 17 degrees C for AI; as well as their in vivo fertility (farrowing rate and litter size of 10,952 AI-sows). SP-SOD-activity was assessed in 311 ejaculates (100 boars) while sperm motility (by CASA), viability and intracellular H2O2 generation in viable spermatozoa (by flow cytometry) were measured at 0 and 72 h of liquid storage. SP-SOD activity was not affected by breed but differed (P amp;lt; 0.001) between boars (n = 50), ranging from 1.16 +/- 0.11 to 7.02 +/- 0.75 IU/mL. Semen Al-doses (n =44) hierarchically grouped (P amp;lt; 0.001) with low SP-SOD activity showed lower (P amp;lt; 0.05) sperm motility and intracellular H2O2 at 72 h of liquid storage. Fertility did not differ between AI-boars (n = 39) hierarchically grouped (P amp;lt; 0.001) with high or low SP-SOD activity. In conclusion, SP-SOD activity is boar dependent and positively related with sperm functionality of liquid stored semen AI-doses. However, this positive effect is not reflected on in vivo fertility post-AI. (C) 2019 Elsevier Inc. All rights reserved.