Post-thaw Addition of Caffeine and/or Pentoxifylline Affect Differently Motility of Horse and Donkey-Cryopreserved Spermatozoa.
Authors: Rota Alessandra, Sabatini Chiara, Przybył Anna, Ciaramelli Alessia, Panzani Duccio, Camillo Francesco
Journal: Journal of equine veterinary science
Summary
# Editorial Summary: Caffeine and Pentoxifylline in Equine Cryopreserved Semen Cryopreservation significantly compromises sperm function in both horses and donkeys, yet few strategies exist to restore motility post-thaw—making this investigation into methylxanthine supplementation particularly relevant for breeding programmes reliant on frozen semen. Researchers thawed cryopreserved semen from 14 stallions and 7 donkeys, then incubated samples in one of six conditions: control, caffeine at 5 or 10 mM, pentoxifylline at 5 or 10 mM, or a combination of both methylxanthines at 5 mM each, with motility parameters assessed immediately post-thaw and at 60 and 120 minutes. In stallions, both total and progressive motility improved significantly with caffeine and pentoxifylline treatment compared to control (particularly at 5 mM concentrations), whilst donkey spermatozoa showed no response to either additive—a species-specific finding that underscores important biological differences between equids. Notably, untreated stallion semen deteriorated far more rapidly during the first hour than donkey semen across all measured parameters, suggesting greater vulnerability to post-thaw stress. Whether these improvements in motility parameters translate into enhanced fertility rates in vivo or through artificial reproduction techniques remains unknown, but the findings warrant further investigation into species-specific optimisation protocols for cryopreserved equine germplasm.
Read the full abstract on PubMed
Practical Takeaways
- •Post-thaw addition of caffeine (5 mM) or pentoxifylline (5-10 mM) can improve motility of cryopreserved stallion semen, potentially beneficial for breeding programs using frozen semen
- •Species differences are significant: these additives do not improve donkey semen parameters, requiring separate optimization strategies for different equine species
- •Clinical impact on pregnancy rates remains unproven; further in vivo and in vitro studies needed before implementing in breeding protocols
Key Findings
- •In horses, total motility was significantly higher with caffeine 5 mM, pentoxifylline 5 mM, pentoxifylline 10 mM, and combined caffeine-pentoxifylline compared to control (P < 0.05)
- •Progressive motility increased only with 5 mM caffeine and 5 mM pentoxifylline in stallions (P < 0.05)
- •No significant differences between control and any treatment groups were observed in donkey semen
- •During first hour of incubation, horse sperm showed sharper decreases in motility parameters than donkey sperm (P < 0.05), indicating species-specific post-thaw responses