Improvement of the quality of boar cryopreservation semen by supplementing with low density lipoprotein in diluents

Low density lipoprotein was added at concentrations of 6%, 7%, 8%, 9% and 10% to the diluents used to freeze boar semen and its effect on the quality of cryopreservation was assessed The results indicated that 9% low density lipoprotein supplementation significantly improved the total motile sperm (p < 0.05). The sperm straight-line velocity increased with the concentration of low density lipoprotein except at the concentration of 10%, at which concentration the sperm velocity declined (p < 0.05). Supplementation at 8% and 9% low density lipoprotein significantly increased plasma membrane integrity (p < 0.05). Compared with control, the low density lipoprotein supplementation significantly improved the percentage of acrosome integrity (p < 0.05). With all parameters measured, the concentration of 9% low density lipoprotein showed a better effect on the quality of boar cryopreservation semen. The sperm DNA was more seriously damaged in the species of Yorkshire than in Duroc.