Optimization of sperm cryopreservation protocol for Basa catfish (Pangasius bocourti)

Area of Science:

• Aquaculture and Reproductive Biology
• Fish Gamete Preservation
• Cryobiology

Background:

• Basa catfish (Pangasius bocourti) aquaculture is economically significant.
• Efficient sperm cryopreservation is crucial for genetic resource management and artificial reproduction in aquaculture species.
• Previous cryopreservation protocols for P. bocourti lack detailed optimization for key parameters.

Purpose of the Study:

• To optimize a comprehensive sperm cryopreservation protocol for Basa catfish (Pangasius bocourti).
• To investigate the effects of various cryoprotectants, thawing conditions, equilibration times, dilution ratios, and freezing methods.
• To determine optimal pre-freezing and post-thaw storage durations.

Main Methods:

• Tested five cryoprotectants (Me2SO, DMF, EG, PG, MA) at 5-15% concentrations.
• Evaluated thawing temperatures (20-60°C) and equilibration times (up to 2 hours).
• Assessed semen/cryomedium dilution ratios (1:1 to 1:9) and freezing techniques (programmable freezer, floating frame).

Main Results:

• 10% propylene glycol (PG) demonstrated the best cryoprotective effect.
• Optimal thawing occurred at 30-40°C, yielding significantly higher post-thaw motility.
• Dilution ratios of 2:1, 1:1, and 1:3 (semen/cryomedium) were superior.
• Cryopreserved sperm maintained motility for 30 minutes post-thaw and could be stored pre-freezing for 24 hours.
• Fertilization rates with cryopreserved sperm (77.5%) were comparable to fresh sperm (80.9%).

Conclusions:

• Established an optimized cryopreservation protocol for Basa catfish sperm.
• Identified key parameters including optimal cryoprotectant, thawing temperature, dilution ratio, and freezing methods.
• The standardized protocol facilitates efficient artificial reproduction and genetic management of P. bocourti.