Stored Stallion Sperm Quality Depends on Sperm Preparation Method in INRA82 or INRA96.
Authors: Papin Johanna, Stuhtmann Gesa, Martinsson Gunilla, Sieme Harald, Lundeheim Nils, Ntallaris Theodoros, Morrell Jane M
Journal: Journal of equine veterinary science
Summary
# Editorial Summary Seminal plasma removal improves stallion sperm longevity during cooled storage, yet aggressive washing protocols risk chromatin damage—a critical consideration when preparing doses for artificial insemination. Researchers compared three preparation methods (single-layer centrifugation, conventional washing, and extension-only controls) across two commercially available extenders (INRA82 and INRA96) using ejaculates from six stallions, monitoring motility, acrosome integrity, morphology, and chromatin fragmentation over 96 hours at 6°C. INRA96 consistently outperformed INRA82 across most parameters, whilst single-layer centrifugation emerged as the superior preparation technique, preserving progressive motility and acrosome status better than both washing and controls, with significantly lower chromatin fragmentation than washed samples at 96 hours. Importantly, single-layer centrifugation reduced tail defects compared to washing, suggesting mechanical damage during conventional centrifugation protocols may be underestimated in routine fertility assessments. For practitioners storing chilled stallion semen prior to breeding, adopting single-layer centrifugation with INRA96 offers demonstrable improvements in sperm viability and genetic integrity without the morphological penalties associated with harsher preparation methods.
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Practical Takeaways
- •Use INRA96 extender over INRA82 for stallion sperm storage to maintain better sperm quality during cooled storage
- •Employ single-layer centrifugation instead of conventional sperm washing when preparing stallion semen for artificial insemination, as it better preserves chromatin integrity and reduces morphological damage
- •SLC is a practical, damage-minimizing alternative to full sperm washing that maintains seminal plasma removal benefits without the mechanical stress of centrifugation-based washing
Key Findings
- •INRA96 extender produced better sperm motility, acrosome status, and normal morphology compared to INRA82 during 96-hour storage at 6°C
- •Single-layer centrifugation (SLC) resulted in higher motility and fewer reacted acrosomes than control (extension only) samples
- •SLC samples had significantly lower fragmented chromatin (5.8% vs 9.6%) compared to washed samples after 96 hours
- •Sperm washing induced more tail defects than SLC, with INRA82-washed samples showing fewer tail defects than INRA96-washed samples