Influences of sorting and cryopreservation on the mitochondrial membrane potential (MMP) and phosphatidylserine (PS) externalization in bovine sperm

• Cryopreservation elevated the percentage of damaged bovine sperm.
• Sorting had no obvious influence on the damage of fresh sperm.
• Freshness of sperm has a great impact on sperm health.

Previously, most studies on sperm apoptosis have been conducted after cryopreservation. There are few reports about the influence of sorting by flow cytometry or the double effects of sorting and cryopreservation on sperm quality. The aim of this study is to evaluate the influences of sorting and cryopreservation treatment on the injury of bovine sperm by the detection of mitochondrial membrane potential (MMP) and phosphatidylserine (PS) externalization (Annexin V/PI), which are two important markers of cellular damage. Results of both MMP and Annexin V/PI indicate that the percentage of damaged sperm was elevated after a single-treatment of cryopreservation and the co-treatment of sorting and cryopreservation. Sorting alone has no obvious influence on fresh sperm according to these two indexes. However, it significantly affects semen samples placed at room temperature (RT) for 12 h and 24 h. This indicates that the freshness of sperm has a great impact on sperm health.