Effects of negative pressure on boar semen quality during liquid storage at 17°C

This study aimed to investigate the influence of negative pressure on boar semen quality during liquid preservation at 17°C. Semen samples from ten large white boars were collected and pooled, divided into four equal parts, and diluted with Modena containing 0.4% (w/v) of bovine serum albumin. The semen samples were placed in a closed container with valve, and a negative pressure was applied for 2–5 minutes using a vacuum pump with a barometer. The control group had no treatment, the P200 group was treated at 200 mbar, the P400 group at 400 mbar, and the P800 group at 800 mbar. During liquid preservation, sperm motility, total antioxidant capacity, and semen H₂O₂ content were analyzed every 24 h. The effective survival time of boar semen during preservation was evaluated. The results indicated that a suitable negative pressure decreased the effects on reactive oxygen species on boar sperm quality during liquid preservation compared with the control group. Among all the groups, the 400 mbar negative pressure group had the highest sperm motility, total antioxidant capacity, and the percentage of spermatozoa with high mitochondrial membrane potential. The P400 group also had semen H₂O₂ content than the other groups. A suitable negative pressure improves sperm quality by reducing oxidative stress and the respiratory metabolism of sperm, and the optimum negative pressure is 400 mbar.