Adding glycine to bull semen before freezing improves the quality of the semen. The researchers tested different amounts of glycine in the semen extender and found that using 5mM of glycine resulted in the highest sperm motility and acrosome integrity after thawing. This means that the sperm were better able to move and maintain their structure after being frozen and thawed. Other aspects of sperm quality, like viability and membrane integrity, were not affected by the glycine supplementation. In conclusion, adding 5mM of glycine to the extender can help improve the quality of cryopreserved bull semen.