Influence of Different Combinations of Permeable and Nonpermeable Cryoprotectants on the Freezing Capacity of Equine Sperm.
Authors: Vafaei Farhad, Kohram Hamid, Zareh-Shahne Ahmad, Ahmad Ejaz, Seifi-Jamadi Afshin
Journal: Journal of equine veterinary science
Summary
# Editorial Summary: Cryoprotectant Combinations for Stallion Sperm Preservation When freezing stallion semen for breeding programmes, the choice of cryoprotectant agents significantly influences post-thaw sperm quality, yet optimal combinations remain incompletely understood. Researchers pooled ejaculates from four Turkmen stallions and evaluated how different permeable cryoprotectants (dimethylacetamide [DMA], dimethylformamide [DMF], and glycerol, each at 5%) performed alongside non-permeable agents (trehalose or sucrose at 50 mM), assessing motility parameters, membrane integrity, viability, and oxidative stress following cryopreservation and thawing. Sperm frozen with DMA demonstrated superior post-thaw total motility, velocity measures, and significantly lower lipid peroxidation (malondialdehyde concentration) compared to both DMF and glycerol; both DMA and DMF substantially outperformed glycerol across most parameters including progressive motility, plasma membrane functionality, and morphological preservation. Notably, trehalose and sucrose showed equivalent efficacy regardless of which permeable agent was used, suggesting these non-permeable cryoprotectants are largely interchangeable, whilst the lack of synergistic interaction between permeable and non-permeable combinations indicates each compound class functions independently. For equine reproduction specialists considering cryopreservation protocols, this evidence supports DMA as a glycerol alternative where available, potentially improving conception rates from frozen-thawed semen in breeding programmes.
Read the full abstract on PubMed
Practical Takeaways
- •DMA or DMF can replace glycerol as cryoprotectants for stallion sperm freezing protocols with improved outcomes in motility and oxidative stress markers
- •Choice of nonpermeating cryoprotectant (trehalose vs sucrose) has minimal impact on frozen-thaw sperm quality, simplifying protocol selection
- •Combining permeable and nonpermeating cryoprotectants does not provide additive benefits for most sperm parameters, informing cost-effective extender formulation
Key Findings
- •DMA (dimethylacetamide) produced significantly higher total motility, straightness, and velocity while reducing lipid peroxidation compared to DMF and glycerol in cryopreserved stallion sperm
- •Both DMA and DMF demonstrated superior sperm motion kinetics, viability, and plasma membrane functionality with lower morphological abnormalities versus glycerol
- •Trehalose and sucrose as nonpermeating cryoprotectants showed no significant differences in post-thaw sperm parameters except for morphological abnormalities
- •No synergistic interaction was found between permeating and nonpermeating cryoprotectant combinations for most post-thaw parameters