This document outlines the standard procedure for freezing semen, which involves: 1) Diluting the semen sample into two parts, with one part containing glycerol and the other not, then gradually combining the parts to achieve the desired final glycerol concentration of 7%. 2) Allowing the diluted semen to equilibrate at 5°C for 4-18 hours. 3) Packaging the equilibrated semen in vials, pellets or straws at 5°C. 4) Freezing the packaged semen by placing straws above liquid nitrogen vapor for 2 minutes before full immersion in liquid nitrogen until use.