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.

Effects of dietary n-6:n-3 fatty acid ratio and vitamin E on semen quality, fatty acid composition and antioxidant status in boars.

The aim of the present study was to evaluate the effects of dietary n-6:n-3 fatty acid (FA) ratio and vitamin E on the semen quality, FA composition and antioxidant status of boars. Forty-eight Landrace boars were randomly distributed in a 3×2 factorial design with three n-6:n-3 FA ratios (14.4, 6.6 and 2.2) by the inclusion of three oil sources (soybean, fish/soybean, fish) and two vitamin E levels (200 and 400mg/kg). During the 8 weeks of treatment, semen parameters were evaluated. Serum, sperm and seminal plasma samples were taken at 0 and 8 weeks to monitor the FA composition and antioxidant status. Results showed that the 6.6 and 2.2 dietary ratios very effectively increased docosahexaenoic acid (DHA) and n-3 polyunsaturated fatty acid (PUFA) and decreased docosapentaenoic acid (DPA) and n-6:n-3 ratio in spermatozoa. The 6.6 dietary ratio contributed to a greater progressive sperm motility (P<0.05) than the 14.4 and 2.2 dietary ratio, and this ratio also enhanced the superoxide dismutase (SOD) and total antioxidant capacity (TAC) (P<0.05) in seminal plasma more significantly than the other two ratios at week 8. Compared with 200mg/kg supplementation of vitamin E, 400mg/kg supplementation of vitamin E increased the progressive sperm motility, SOD of sperm, TAC and SOD of seminal plasma and serum, and decreased sperm malondialdehyde (MDA) (P<0.05). In conclusion, the 6.6 dietary ratio and 400mg/kg vitamin E supplementation improve progressive sperm motility by modifying the sperm FA composition and antioxidant status.