A simplified fixed-time insemination protocol using frozen-thawed stallion spermatozoa stored at 17°C for up to 24 h before insemination.
Authors: Morris Lee, Harteveld Ria, Gibb Zamira
Journal: Equine veterinary journal
Summary
# Editorial Summary Frozen-thawed stallion semen typically delivers pregnancy rates of only 40–60% per cycle and demands rigorous management protocols, making it an impractical option for many breeding programmes. Lee, Harteveld and Gibb investigated whether microfluidic processing followed by chilled storage (17°C) could extend the viable storage window of thawed semen, ultimately reducing the logistical burden of fixed-time insemination. Their work comprised three experiments: initial evaluation of sperm motility following conventional centrifugation and 48-hour storage; assessment of motility after microfluidic sorting with 24-hour storage; and a fertility trial using 42 mare cycles inseminated at 6, 16 and 24 hours post-thaw. Whilst individual stallion genotype significantly influenced motility outcomes and centrifugation alone caused progressive motility decline over time, microfluidic sorting protected sperm function throughout the 24-hour storage period regardless of which resuspension medium was used. Critically, the embryo recovery rate remained stable at 52% across all storage intervals, meeting established benchmarks for frozen semen use without any apparent loss of fertility. For practitioners managing commercial breeding programmes, these findings suggest that microfluidic sorting technology offers a practical pathway to simplify frozen semen handling: semen can be processed and stored for up to 24 hours at 17°C with confidence, permitting greater flexibility in scheduling inseminations and reducing the need for intensive real-time management. However, the small cohort size (3 stallions, 42 cycles) warrants cautious interpretation; validation across larger populations and diverse stallion genetics would strengthen confidence in adopting this protocol clinically.
Read the full abstract on PubMed
Practical Takeaways
- •Microfluidic sorting combined with 17°C storage allows simplified fixed-time insemination protocols with frozen semen, potentially reducing intensive management requirements compared to standard protocols
- •Embryo recovery rates of 52% after microfluidic processing and 24-hour storage are comparable to or better than conventional frozen semen insemination (40-60% baseline), offering practical flexibility in breeding timing
- •Choice between Botusemen Gold® and SpermSafe® storage media does not significantly impact motility, allowing practitioners to select based on cost or availability without compromising fertility outcomes
Key Findings
- •Microfluidic sorting of frozen-thawed spermatozoa prevented motility decline during 24-hour storage at 17°C, unlike centrifugation-only method which showed significant decline by 48 hours
- •Storage media (Botusemen Gold® vs SpermSafe®) had no significant effect on sperm motility parameters
- •Fixed-time insemination protocol achieved 52% embryo recovery rate (22/42 cycles) after microfluidic sorting and up to 24-hour storage at 17°C
- •Stallion genetics significantly influenced post-thaw sperm motility, independent of processing method