87 Kinematic and morphological properties of Large White boar sperm under induced oxidative stress

Boar sperm have been proven to have a high content of polyunsaturated fatty acids, making them susceptible to oxidative stress. The present study aimed to evaluate the properties of sperm motility and viability under induced oxidative stress (hydrogen peroxide, H₂O₂) over 3 h duration of liquid semen storage in vitro, on semen from Large White boars. Ten ejaculates per boar were collected from each of three Large White boars using the gloved hand method. Semen was transported to the laboratory for evaluation. For semen treatment, 10 mmol mL⁻¹ H₂O₂ stock solution was prepared in prewarmed (37°C) Medium 199 and kept at 5°C until use. During the experiment, semen was pooled and divided into six parts and treated with prewarmed (37°C) H₂O₂ stock solution supplemented with 5 mmol mL⁻¹ glutathione (GSH) and 5 mmol mL⁻¹ dithiothreitol (DTT) to make six treatments (control, 5 µM H₂O₂, 5 µM DTT, 5 µM GSH, 5 µM H₂O₂ + DTT, 5 µM H₂O₂ + GSH) to a final sperm concentration of ∼13 × 10⁶ mL⁻¹. The treatments were incubated at 30°C for 3 h in a humidified atmosphere of 5% CO₂ in air. Semen was evaluated for sperm motility and velocity using a computer-aided sperm analyser system. Eosin-nigrosin staining was used to evaluate sperm viability under the microscope (100× magnification); 200 sperm were counted for each stained slide. Data were analysed using the GLM procedure. Treatment means were separated using Fisher’s protected t-test least significant difference (l.s.d.) at a 0.05 level of significance. Raw semen volume was 313 mL, semen pH was 7.5, sperm concentration was 199.5 × 10⁶ mL⁻¹, sperm total motility (TM) was 97.9 ± 2.1%, and viable sperm was 92.8%. After 3 h of incubation, the sperm TM among treatments ranged from 86.7 to 93.3%. The control treatment recorded high sperm progressive motility (PM; 71.2 ± 17.8) and rapid motility (RAP; 64.9 ± 21.6) after 3 h of incubation compared with H₂O₂ (49.8 ± 16.8; 40.7 ± 19.6) and DTT (54.1 ± 12.6; 43.4 ± 16.2) treated semen, respectively (P < 0.05). Supplementation of DTT (64.7 ± 14.2) to H₂O₂ (49.8 ± 16.8)-treated semen significantly improved sperm PM by 14.8%, while GSH treatment (59.3 ± 14.3) numerically improved sperm PM by 9.4% after the incubation period. Supplementation of GSH (31.7 ± 10.3) to H₂O₂ (24.6 ± 5.1)-treated semen improved straight line velocity by 7.1% after incubation (P < 0.05). Sperm viability of above 70% was recorded among treatments after incubation. The DTT (85.1 ± 6.5) and control treatments (86.0 ± 4.2) had higher viable sperm after incubation (P < 0.05). In conclusion, Large White boar semen was highly susceptible to H₂O₂-induced oxidative stress as shown by compromised sperm motility, kinematic parameters, and viability. However, supplementation of antioxidants can reduce those effects.