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

I. F. Canisso, G. R. Carvalho, Mina Clare Gwynne Davies-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 0.5 ml straws and chilled to 5°C for 1 h, after which samples were either evaluated (chilled semen) or placed above liquid nitrogen for 20 min 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
Pages (from-to)179-183
Number of pages5
JournalEquine Veterinary Journal
Issue number2
Early online date05 Jul 2010
Publication statusPublished - Mar 2011


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