Cryopreservation techniques for blue catfish, Ictalurus furcatus, sperm using 2.5 mL straws

Area of Science:

• Aquaculture and Reproductive Biology
• Cryobiology
• Fish Sperm Preservation

Background:

• Effective cryopreservation of fish sperm is crucial for aquaculture, selective breeding, and genetic resource management.
• Optimizing cryoprotective agent (CPA) combinations and freezing rates is essential for maintaining sperm quality post-thaw.

Purpose of the Study:

• To evaluate the impact of permeating (methanol) and non-permeating (trehalose, lactose) cryoprotectant agents (CPAs) and various freezing rates on blue catfish (Ictalurus furcatus) sperm motility and velocity (VCL).
• To identify optimal cryopreservation protocols for blue catfish sperm.

Main Methods:

• Sperm samples from blue catfish were cryopreserved in 2.5 mL straws using different permeating CPAs (dimethyl sulfoxide, methanol) and non-permeating CPAs (trehalose, lactose) at specified concentrations.
• Sperm were frozen at various rates (-1.0, -5.0, -10, -20 °C/min).
• Post-thaw sperm motility and VCL were assessed using standard kinematic analysis.

Main Results:

• Sperm frozen with methanol at -20 °C/min exhibited the highest post-thaw kinematics (VCL = 141.8 ± 18.5 μm/s, motility = 30.5 ± 12.2 %), comparable to fresh sperm (VCL = 162.7 ± 5.4 μm/s, motility = 50.2 ± 15.1 %).
• Non-permeating CPAs did not enhance VCL; lactose (5-10%) and trehalose (300 mmol/L) inhibited motility.
• Trehalose at 100 mmol/L significantly increased sperm motility by 41.2% compared to controls without non-permeating CPAs.

Conclusions:

• Methanol combined with rapid freezing (-20 °C/min) is a highly effective method for cryopreserving blue catfish sperm, maintaining significant motility and velocity.
• Trehalose at 100 mmol/L shows promise for enhancing sperm motility during cryopreservation.
• These findings support the development of advanced cryopreservation technologies for blue catfish, benefiting selective breeding and commercial aquaculture.