Does MnTBAP ameliorate DNA fragmentation and in vivo fertility of frozen-thawed Arabian stallion sperm?

This study investigates whether adding an antioxidant, MnTBAP, to the semen of Arabian stallions before freezing can improve its quality post-thawing and also increase success rates of in vivo fertility. The results indicate that a dose of 200 µM of MnTBAP resulted in better sperm quality, reduced oxidative stress and protected against DNA fragmentation, but didn’t lead to a significant increase in pregnancy rates.

Methodology

• Twenty-one semen samples were obtained (three stallions, seven samples each) and diluted with an extender containing varying levels of MnTBAP (0, 100, 200, 300 μM) before being frozen.
• After thawing, the researchers measured several parameters associated with semen quality which include sperm motility, viability, membrane integrity, acrosome abnormalities, lipid peroxidation and DNA fragmentation.
• Furthermore, fertility trials were implemented using 60 deep horn inseminations with twelve mares and frozen semen from the control group and the group treated with 200 µM – MnTBAP.

Results & Findings

• Inclusion of MnTBAP in the extender improved stallion semen quality parameters in a dose-dependent manner. However, the improvement was not linear with increasing doses of MnTBAP. Instead, a dose of 200µM resulted in the best outcomes in terms of sperm motility, viability, and membrane integrity.
• The MnTBAP antioxidant was found to be effective in reducing DNA fragmentation, indicating its role in protecting stallion sperm from oxidative stress during the freeze-thawing process.
• Interestingly, higher amounts of MnTBAP (300 µM) led to inverse effects on sperm parameters suggesting overconsumption of antioxidants could cause damage instead of being beneficial.
• No significant difference in pregnancy rates were observed between the control group (30% rate) and the MnTBAP-treated group (46.66% rate).

Conclusion

• The results from this research indicate that MnTBAP can reduce oxidative stress and protect against DNA fragmentation in Arabian stallion sperm during the freezing and thawing process. This can result in improved sperm quality, especially at the optimum dosage of 200µM.
• However, despite these improvements in sperm quality, there was no significant improvement in fertility rates with the use of MnTBAP compared to the control group. This suggests that while antioxidants may improve sperm quality, other factors could be influencing the success rates of in vivo fertility.