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

Our objectives were to investigate how permeating cryoprotectant agents (CPAs; dimethyl sulfoxide, methanol), non-permeating CPAs (trehalose at 100 and 300 mmol/L; lactose at 5 and 10 %), and freezing rates (-1.0, -5.0, -10, -20 °C/min) impact post-thaw sperm motility and velocity (VCL) in blue catfish (Ictalurus furcatus) using 2.5 mL straws. Sperm frozen with methanol at -20 °C/min had the highest kinematics (VCL = 141.8 ± 18.5 μm/s, motility = 30.5 ± 12.2 %), and showed similar results to fresh sperm (VCL = 162.7 ± 5.4 μm/s, motility = 50.2 ± 15.1 %). Adding non-permeating CPAs did not improve VCL, and sperm motility was inhibited by lactose 5-10 % and trehalose 300 mmol/L. However, trehalose 100 mmol/L increased motility by 41.2 %, relative to straws without the addition of non-permeating CPAs. Development of this new freezing technology has merit for selective breeding, large research projects, and commercial-scale production for an economically important farm animal.