Effect of Long-Term Storage at Different Temperatures on the Quality of Liquid Boar Semen

In this study the effect of long‐term storage of liquid boar semen at different temperatures on motility, acrosome integrity and pH was investigated. Additionally, individual variation in sperm tolerance to storage at 10°C were examined. Beltsville Thawing Solution‐diluted AI doses from 16 randomly chosen Norwegian Landrace AI boars with proven fertility were split into subsamples and stored at 25, 20, 15 and 10°C, respectively. After 0, 24, 48, 72 and 96 h of storage, sperm motility, acrosome integrity and pH were determined. After 96 h, the initial percentage of motile sperm (77.8%) was significantly reduced to 52.2, 58.8, 50.9 and 42.8% by storage at 25, 20, 15 and 10°C, respectively. After an identical period of time, the percentage of acrosome intact sperm (95.8%) at time 0 became significantly reduced to 91.3, 91.3, 81.5 and 68.3% by storage at 25, 20, 15 and 10°C, respectively. The initial pH (7.21) decreased significantly to 6.96 and 7.06 after 96 h storage at 25 and 20°C, and increased not significantly to 7.25 for storage at 15°C and significantly to 7.29 at 10°C. In conclusion, the results from this study show that, according to the variables studied, 20°C is the least harmful of the four temperatures tested for the long‐term liquid storage of boar semen. Furthermore, remarkable differences in the individual resistance of boar semen to long‐term storage at 10°C were observed.