Seminal parameters and field fertility of cryopreserved donkey jack semen after insemination of horse mares

I. F. Canisso, G. R. Carvalho, M. Davis Morel, P. G. Ker, A. L. Rodrigues, E. C. Silva, M. A.Coutinho Da Silva

Research output: Contribution to journalArticlepeer-review


Reasons for performing study: As mule production is often concentrated in remote areas of the world, a simplified semen cryopreservation protocol is required. Aim: To compare the seminal parameters of cryopreserved donkey semen in lactose-EDTA and lactose-yolk extenders and the fertility rates on horse mares. Methods: Trial 1: Sperm total and progressive motility, vigour (scale 0-5), morphology (major and minor defects) and plasma membrane integrity (HOST) were evaluated in 25 ejaculates from 5 donkey jacks immediately after collection (raw), after chilling to 5°C (chilled) and after freezing/thawing. The semen was mixed with skimmed-milk extender, centrifuged, and then re-suspended in lactose-EDTA or lactose-yolk extender. Semen was loaded into 0.5ml straws and chilled to 5°C for 1h, after which samples were either evaluated (chilled semen) or placed above liquid nitrogen for 20min prior to immersion. Seminal parameters were evaluated by ANOVA and Tukey's test. Trial 2: Cryopreserved semen from 3 males was used to inseminate 53 mares at 60 oestrous cycles randomly assigned to lactose-yolk (n = 30 cycles) or lactose-EDTA (n = 30 cycles) extenders. Pregnancy diagnosis was performed 15 and 25 days post ovulation. The pregnancy rates were compared using Chi-squared tests. Results: Trial 1: No significant differences were evident in any seminal parameters between extenders after either chilling or cryopreservation. Total and progressive motility were significantly (P<0.05) lower in cryopreserved semen than raw and chilled semen for both extenders. Trial 2: Pregnancy rates did not significantly differ between extenders (lactose-EDTA extender 53.33 and 43.33%; lactose-yolk 50.0 and 46.66% for Days 15 and 25 post ovulation, respectively). Conclusions: Cryopreservation of donkey semen using the simplified lactose-yolk extender resulted in similar seminal parameters and fertility rates when compared to lactose-EDTA extender. Potential relevance: Lactose-yolk extender may be advocated as a simple, easy to prepare extender, for use in geographically isolated enterprises producing mules throughout the world.

Original languageEnglish (US)
Pages (from-to)179-183
Number of pages5
JournalEquine veterinary journal
Issue number2
StatePublished - Mar 2011
Externally publishedYes


  • Artificial insemination
  • Cryopreservation
  • Donkey
  • Horse
  • Mare
  • Mule production

ASJC Scopus subject areas

  • Equine


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