① Write the date and group number in the stopper of the straw tube.
② Dispense 3 mL of cryoprotectant solution into a 15mL tube
③ 1 mL (5-fold diluted) of sperm mixed well
④ Insert a slightly cut blue tip attached to the pipetman at the plug side of the straw tube, and aspirate the sperm diluent until the straw is full (if it comes to the stopper, it cannot inhale naturally).
⑤ Push the powder into the mouth opposite the straw plug.
⑥ Perform the same procedure until the sperm diluent is exhausted.
⑦ Incubate at 4°C for 1-2 minutes and let sit on a holder on liquid nitrogen.
⑧ After 15 minutes or longer on the holder, put into liquid nitrogen.
After completion of all experiments, straws in liquid nitrogen were collected and stored in a tank.