Comparison of different cryopreservation methods for horse and donkey embryos.
Authors: Pérez-Marín C C, Vizuete G, Vazquez-Martinez R, Galisteo J J
Journal: Equine veterinary journal
Summary
# Editorial Summary: Cryopreservation Methods for Equine Embryos Preserving equine embryos through freezing offers significant potential for breeding programmes, yet limited evidence exists comparing the effectiveness of different cryopreservation techniques in horses and donkeys. Pérez-Marín and colleagues conducted a randomised controlled trial using embryos collected from 19 mares and 16 jennies at days 6.5–7.5 post-ovulation, subjecting them to slow freezing (using ethylene glycol) or vitrification protocols with various cryoprotectant combinations, delivered via either straw or Fibreplug, before assessing cell viability, apoptosis, fragmented nuclei, and cytoskeleton integrity after thawing. Both cryopreservation methods caused significant embryo quality deterioration compared to controls; however, no meaningful difference emerged between slow freezing and vitrification in horses, whilst donkey embryos showed notably lower susceptibility to vitrification damage, particularly when using Fibrepluk with 7.0 mol/L ethylene glycol, which minimised nonviable and apoptotic cells. The findings suggest that donkey embryos demonstrate greater cryotolerance than horse embryos—a distinction worth noting for practitioners developing breeding strategies—and that Fibreplug delivery with higher ethylene glycol concentrations may offer advantages for donkey embryo preservation, though further investigation with larger sample sizes remains necessary to establish robust clinical protocols.
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Practical Takeaways
- •Both vitrification and slow freezing are viable cryopreservation methods for equine embryos with comparable outcomes; choice may depend on equipment availability and species
- •Donkey embryos tolerate vitrification better than horse embryos, suggesting species-specific protocols may optimize breeding program success
- •For donkey embryo preservation, Fibreplug with 7.0 mol/L ethylene glycol solution is the preferred cryopreservation method to maximize post-thaw viability
Key Findings
- •Cryopreservation by both slow freezing and vitrification resulted in significant decreases in embryo quality compared to control (P<0.05)
- •No significant differences in cell damage were detected between slow freezing and vitrification protocols in horse or donkey embryos
- •Donkey embryos showed lower susceptibility to vitrification damage than horse embryos, with fewer nonviable and apoptotic cells
- •Fibreplug with 7.0 mol/L EG produced the best outcomes in donkey embryos, with fewer nonviable and apoptotic cells (P<0.05)