L-Proline: An Effective Agent for Frozen and Post-thawed Donkey Semen Storage.

The research explores the impact of L-proline, an important amino acid, on the quality of donkey semen during freezing and after thawing. The study found evidence that the use of L-proline helps improve both the quality of the frozen and post-thawed semen samples and the pregnancy rates in the animals used for the study.

Research Methodology

• The study involved the use of semen samples from six male donkeys (jacks). These samples were preserved using various concentrations (0-80 mM) of L-proline as additives.
• Once the samples were thawed, they were placed in an L-proline medium and kept in a controlled environment (37°C) for a duration of 10 hours.
• The quality of the preserved semen was evaluated based on several factors. These include motility parameters, mitochondrial membrane potential (MMP), and the structural integrities of plasma membrane, acrosome, and chromatin in the post-thawed samples.
• In addition, Reactive Oxygen Species (ROS) content was also analyzed after the incubation period.
• For evaluating the efficacy on fertility, 135 female donkeys (jennies) were categorized into three groups: Group I (cryopreservation extender included 30mM L-proline), Group II (culture medium included 40mM L-proline), and a control group. After 30 days of ovulation, ultrasound scanning was used to diagnose pregnancy.

Outcomes of the Research

• The study outcomes pointed towards a positive impact of L-proline on semen quality. The semen samples that had been frozen with L-proline showed significantly better motility parameters, and improved acrosome and chromatin structure integrities than the control group.
• L-proline was found to have a protective effect from Reactive Oxygen Species (ROS), which can damage the structural integrity of sperm, leading to impaired fertility. The L-proline groups showed significantly less ROS accumulation as compared to the control group.
• Pregnancy rates in the animal groups with added L-proline were higher. The control group had a pregnancy rate of 28.85%, while the groups with L-proline additives had rates of 40% and 36.84%.

Conclusion

• The research concludes that L-proline, when added to the extender used in semen cryopreservation, can improve the quality of both frozen and post-thawed donkey semen. These benefits include improved sperm motility parameters, and the structural integrity of acrosome, and chromatin structures even post-thawing.
• The reduction in ROS accumulation further contributes to improving the semen quality and thus, L-proline proves to be a beneficial agent for preserving donkey spermatozoa, either during freezing or after thawing.
• The research also suggests that extenders with 30-40 mM L-proline may be optimal for achieving these benefits.