Supplementing oregano essential oil to boar diet with strengthened fish oil: Effects on semen antioxidant status and semen quality parameters

Previous research has shown benefits of dietary fish oil supplementation on semen quality of boars. However, little is known about how antioxidant protects lipid peroxidation on spermatozoa from n-3 polyunsaturated fatty acid (PUFA) addition. This study evaluated the effect of oregano essential oil (OEO) supplementation on semen antioxidant status and semen quality in boars fed a diet enriched with fish oil. Thirty-four mature boars of proven fertility, received daily 2.5 kg basal diet top-dressed with 45 g soybean oil and 15 g fish oil to meet the n-3 PUFA requirement of spermatozoa, randomly allocated to one of four groups supplemented with 100 mg α-tocopheryl acetate kg^-1 (control), or 250 or 500 or 750 mg OEO kg^-1 for 16 weeks. Semen was collected at weeks 0, 8, 12 and 16 for measurements of sperm production, motion characteristics, sperm α-tocopherol content, antioxidant enzyme activities, reactive oxygen species (ROS), DNA damage (8-hydroxydeoxyguanosine, 8-OHdG), lipoperoxidation (malondialdehyde, MDA) and seminal total antioxidant capacity (TAC). Sperm production and motion characteristics were similar (p > .05) among groups throughout the experimental week 16, but increased (p < .01) with experimental week. Although higher α-tocopherol content and superoxide dismutase (SOD) activities were in OEO group spermatozoa, feeding diet with 500 mg/kg OEO resulted in elevation in seminal TAC, decrease in sperm ROS, MDA and 8-OHdG than control group (p < .05). Overall, these results support the view that oregano essential oil has a positive effect on antioxidant capacity in boar when used fish oil.