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 (control), or 250 or 500 or 750 mg OEO kg 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.
This study was aimed to evaluate the effects of dietary n-6:n-3 ratio and Vitamin E on the membrane properties and motility characteristics of spermatozoa in boars. Forty Duroc boars were randomly distributed in a 2 × 2 factorial design with two n-6:n-3 ratios (14.4 and 6.6) and two Vitamin E levels (200 and 400 mg kg−1). During 16 weeks of treatment, fresh semen was collected at weeks 0, 8, 12, and 16 for measurements of motility characteristics, contents of fatty acids, membrane properties (membrane fluidity and membrane integrity), and lipid peroxidation of the spermatozoa. The semen was diluted in Beltsville Thawing Solution (BTS) extender and stored at 17°C, and the sperm motility was assessed at 12, 36, 72, and 120 h of storage. The 6.6 n-6:n-3 dietary ratio increased the contents of n-3 polyunsaturated fatty acids (PUFAs) and docosahexaenoic acid (DHA) and improved the membrane integrity and membrane fluidity of the spermatozoa, resulting in notably increased total motility, sperm progressive motility, and velocity parameters of fresh semen. Feeding diet with Vitamin E (400 mg kg−1) prevented sperm lipid peroxidation, and resulted in higher total motility and sperm progressive motility in fresh and liquid stored semen. In conclusion, the adjustment of n-6:n-3 ratio (6.6) and supply of Vitamin E (400 mg kg−1) successfully improved sperm motility characteristics and thus may be beneficial to the fertility of boars, which might be due to the modification of the physical and functional properties of spermatozoa membrane in response to dietary supplementation.
A 2×2 factorial experiment (10 boars per treatment) was conducted for 16 weeks to evaluate the effects of the dietary n-6:n-3 ratio (14:1 vs 6:1) and vitamin E (200 vs 400mg kg) on boar sperm morphology and oxidative stress. Sperm mitochondrial membrane potential (MMP), reactive oxygen species (ROS), DNA damage (8-hydroxydeoxyguanosine; 8-OHdG), seminal lipoperoxidation (malondialdehyde; MDA) and antioxidant capacity in the serum, spermatozoa and seminal plasma were assessed as indicators of oxidative stress. Sperm production was similar among groups but increased (P<0.05) throughout the 16 weeks of the study. Although sperm α-tocopherol content, ROS and seminal MDA did not differ between the two dietary n-6:n-3 ratio treatments, enhanced antioxidant enzyme activity and MMP, but decreased 8-OHdG, were found in spermatozoa from boars consuming the 6:1 diet. The diet with the 6:1 ratio positively affected sperm morphology at Weeks 12 and 16 (P<0.05). The α-tocopherol content and antioxidant capacity increased in boars with increasing levels of vitamin E supplementation. Compared with low-dose vitamin E, high-dose vitamin E supplementation improved sperm morphology. Overall, the results indicate that an n-6:n-3 ratio of 6:1 and 400 mg/kg vitamin E have beneficial effects on sperm morphology by improving antioxidative stress.
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