Seminal parameters and field fertility of cryopreserved donkey jack semen after insemination of horse mares.
Authors: Canisso I F, Carvalho G R, Morel M Davis, Ker P G, Rodrigues A L, Silva E C, Coutinho Da Silva M A
Journal: Equine veterinary journal
Summary
# Editorial Summary: Cryopreserved Donkey Semen for Mule Production Mule production in remote regions demands practical solutions for preserving jack semen, yet comparative data on extender protocols has been limited. Researchers evaluated two extender formulations—lactose-EDTA and lactose-yolk—by measuring sperm motility, vigour, morphology and membrane integrity across 25 ejaculates from five donkeys at three stages (fresh, chilled, and post-thaw), then assessed field fertility by inseminating 53 mares across 60 oestrous cycles. Cryopreservation reduced total and progressive motility significantly in both groups compared to fresh and chilled semen, yet pregnancy rates remained comparable between extenders at 43–53% by day 15 post ovulation and 43–47% by day 25. The lactose-yolk formulation performed equivalently to the more complex lactose-EDTA protocol, offering distinct advantages for resource-limited settings where preparation simplicity and cost-effectiveness are critical. For practitioners in geographically isolated areas, this finding validates the use of lactose-yolk extender as a reliable, straightforward option that does not compromise fertility outcomes in cross-species breeding programmes.
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Practical Takeaways
- •Lactose-yolk extender is a viable, simple alternative to lactose-EDTA for cryopreserving donkey semen in remote mule production areas with limited laboratory infrastructure
- •Field fertility rates (~50% pregnancy on Day 15) are clinically acceptable with either extender, making lactose-yolk preferable due to easier preparation and lower cost
- •Expect post-thaw motility reductions compared to fresh semen, but this does not compromise field fertility when using optimal insemination protocols
Key Findings
- •No significant differences in seminal parameters between lactose-EDTA and lactose-yolk extenders after chilling or cryopreservation
- •Total and progressive motility were significantly lower in cryopreserved semen compared to raw and chilled semen (P<0.05)
- •Pregnancy rates did not significantly differ between extenders (lactose-EDTA 53.33% and 43.33%; lactose-yolk 50.0% and 46.66% at Days 15 and 25 post-ovulation respectively)
- •Simplified lactose-yolk extender produced equivalent fertility outcomes to lactose-EDTA extender for donkey semen cryopreservation