Improvement of common carp (Cyprinus carpio) sperm cryopreservation using a programable freezer

Area of Science:

• Aquaculture
• Reproductive Biology
• Cryopreservation Technology

Background:

• Cryopreservation of fish sperm is crucial for aquaculture genetic resource management.
• Scalable and efficient methods are needed for large-volume sperm preservation.

Purpose of the Study:

• To evaluate the efficacy of a programmable freezer for large-scale common carp sperm cryopreservation.
• To optimize cryopreservation parameters including equilibration time, extenders, and dilution ratios.
• To assess post-thaw sperm quality and fertilizing capacity.

Main Methods:

• Investigated effects of equilibration times (up to 60 min) on sperm motility.
• Compared conventional vs. programmable freezer methods.
• Tested various extenders (sugar-based grayling extender) and dilution ratios (1:9, 1:20).
• Evaluated activating solution for cyprinids (ASC) and post-thaw storage intervals (6 hours).

Main Results:

• No significant decrease in motility, curvilinear velocity (VCL), or straightness (STR) during 60 min equilibration.
• Programmable freezer yielded comparable motility parameters to conventional methods.
• Sugar-based extenders and specific dilution ratios maximized motility and VCL.
• Activating solution for cyprinids (ASC) extended sperm movement duration.
• Sperm agglutination observed during large-volume cryopreservation, impacting fertilizing capacity (32% vs. 73% in control).

Conclusions:

• Programmable freezers are suitable for large-scale cryopreservation of common carp sperm.
• Optimized extenders and ratios enhance post-thaw sperm quality.
• Sperm agglutination remains a challenge affecting fertilizing capacity in scaled-up processes.