Towards standardization of the cryopreservation procedure of cultured pikeperch (Sander lucioperca) semen

Within the study, attempts towards standardized cryopreservation procedure for cultured pikeperch semen were undertaken. The specific aims of this study were to examine the effects of final glucose and sperm concentrations on the cryopreservation success of cultured pikeperch semen measured by sperm quality indices. We also examined the effect of different solutions for activation of sperm motility as well as tested the effect of the dilution of semen in Kurokura solution on the cryopreservation success of pikeperch. The final glucose concentrations within the range 0.11?0.15 M in 7.5% methanol achieved good results for the percentage of sperm motility after freezing/thawing, with the highest values at 0.13 M (44 ? 12%). The highest sperm motility after freezing/thawing (56?58%) was observed within the range of 3.0 to 4.0 ? 109 spermatozoa ml- 1. Dilution of semen in seminal plasma resulted in activation of spontaneous sperm motility. Moreover, the extender used for cryopreservation caused activation of sperm motility at a level similar to that of an activation solution. Cryopreserved sperm was characterized by sperm motility similar to that of equilibrated semen. A significant decrease in the sperm motility was recorded in samples not diluted in immobilizing solution after 10 min of postthaw storage compared to values recorded immediately after thawing. These differences were not observed in semen samples diluted in Kurokura solution. In our opinion, development of standardized cryopreservation protocol presented in this study is a prerequisite for the future implementation of cryopreserved semen in hatchery practice. However, control of spontaneous motility seems to be an important challenge for further improvement of cryopreservation techniques for pikeperch semen.

Automated summary

This study aimed to investigate the effects of final glucose and sperm concentrations, different activation solutions for sperm motility, and dilution of semen on the cryopreservation success of cultured pikeperch semen. Results showed that specific concentrations and dilution methods had significant impacts on sperm motility and successful cryopreservation. Future efforts should focus on controlling spontaneous motility to further improve cryopreservation techniques for pikeperch semen.