Fatty acid composition of boar semen and effects of feed supplementation on semen quality

Abstract

EXP I was conducted to determine the differences in lipid and fatty acid (FA) composition of boar sperm and seminal plasma in the ejaculates of boars having different sperm motilities. Semen was collected from two groups of boars having >60% (n=53) and <60% (n=53) sperm motility and separated the sperm from the seminal plasma. Both fractions were kept in -20°C until analyzed for lipid content and FA profile by gas liquid chromatography. Total antioxidant status (TAS) of seminal plasma was determined using a commercial kit. The results demonstrated that there were differences in sperm total lipids, cholesterol, saturated fatty acids (SFA), phospholipids, n-3 polyunsaturated fatty acids (PUFA), docosahexaenoic acid (DHA) and the ratio of n-6:n-3 PUFA between normal and low sperm motility boars (P<0.05), and there were positive correlations among total lipids, cholesterol, phospholipids, PUFA, DHA, n-3 PUFA and TAS of seminal plasma with sperm motility (n=159; P<0.05: r=0.53, 0.60, 0.73, 0.57, 0.42, 0.56 respectively), viability (n=159; P<0.05; r=0.16, 0.28, 0.38 , 0.33, 0.24, 0.28 respectively), normal morphology (n=159; P<0.05; r=0.34, 0.63, 0.75, 0.57, 0.41, 0.54 respectively) and normal plasma membrane (n=159; P<0.05; r=0.34, 0.63, 0.76, 0.59, 0.43, 0.58 respectively). Therefore, these results indicated that lipid composition of boar sperm can influence sperm motility, viability, normal morphology and plasma membrane integrity. EXP II was conducted to compare viability, lipid peroxidation, fatty acid composition of boar spermatozoa and antioxidant capacity of seminal plasma between >50% (n=10) and <50% (n=10) of sperm motility groups at 24 h of cool storage. Semen was collected from all boars once a week for 3 wks and the semen evaluated for motility, sperm concentration, and total number of sperm, percentage of normal morphology and membrane permeability, and viability. Sperm was extracted and analysed for lipid profiles, lipid peroxide and total antioxidant was determine in the extender at 0 and 24 h. The results demonstrated the decreasing of total lipid, proportion of cholesterol in sperm membranes, TAS and showed that increasing of LPO level have a cause in reduction in motility, viability, membrane permeability and hence, storability of sperm EXP III was conducted to determine the effect of fish oil, vitamins and selenium on-top feed supplemented on boar spermatozoa lipid composition and semen quality. Twenty one boars were assigned for this experiment. All boars were randomly divided into three experimental groups: 1) supplemented diet for 8 weeks (n=7); 2) supplemented diet for 16 weeks (n=7) and 3) control (n=7). Fish oil (40 ml), vitamin E (480 iu), vitamin C (2,400 mg) and selenium (0.3 mg) were given once a day by on-top feeding. The semen was collected from all boars using the glove-hand method once a week starting from 7 weeks prior to the supplementation and continues for a total of 23 collections per boar. Semen was evaluated and centrifuged to separate the sperm from seminal plasma and kept at -20°C until analyzed sperm pellet for lipid content, FA profile. The seminal plasma was analyzed for total antioxidant status and glutathione peroxidase (GPX) using a commercial kit. The results indicated that, when compared among the control group and groups supplemented with fish oil for 8 and 16 weeks, the number of total sperm (70.84 vs. 71.69 and 71.35 x109 sperm respectively; P<0.05), semen volume (290.14 vs. 341.60 and 326.24 ml respectively; P<0.05), Proportion of DHA (14.91 vs. 16.21 and 16.16% respectively; P<0.05), and total n-3 (14.12 vs. 16.82 and 16.95% respectively; P<0.05) in sperm composition were increased in boar fed a supplemented diet. Duration of ejaculation (374.82 vs. 439.01 and 419.30 sec respectively; P<0.05) was longer and glutathione peroxidase in seminal plasma (1.22 vs. 1.45 and 1.51 mmol/ml respectively; P<0.05) was improved, in the boars fed a diet supplemented diet comparing with the control group.