Daily Sperm Output, Spermatogenic Efficiency, and Sexual Behavior of Dezhou Donkey Jacks Mounting Jennies in Estrus.
Authors: Magalhaes Humberto B, Canuto Lucas E F, Zhao Fuwei, Li Min, Li Xuexian, Ji Chuanliang, Canisso Igor F
Journal: Journal of equine veterinary science
Summary
# Editorial Summary: Daily Sperm Output in Breeding Donkey Jacks Researchers at institutions in China and Brazil evaluated semen production and mating behaviour in eight mature Dezhou donkey jacks over ten consecutive days of collection, using jennies in natural oestrus as stimulus animals. Testicular volume was calculated using two different equations and compared against actual daily sperm output (measured from days 8–10 of collection) to assess spermatogenic efficiency, whilst sexual behaviour and semen parameters were monitored throughout. Although sexual behaviour and progressive sperm motility remained consistent across collection days, total sperm numbers and concentration declined significantly over the ten-day period; actual daily sperm output averaged 9.1 ± 4.1 billion, yet predicted output varied widely (4.7–18 billion depending on the calculation method used), resulting in spermatogenic efficiency ranging from 50–150% between individual jacks. For breeding purposes, this output could yield 15–47 inseminating doses per day for on-site breeding (at 300–500 million progressively motile sperm per dose) or 4–14 cooled-shipped doses (at 1 billion progressively motile sperm per dose). These findings indicate that routine semen collection does not compromise sexual function or sperm motility in clinically normal donkeys, though practitioners should recognise that testicular volume calculations significantly influence predicted sperm production estimates, and that individual variation in spermatogenic efficiency—some jacks operating at 150% predicted output—warrants consideration when planning assisted reproductive programmes in donkey breeding enterprises.
Read the full abstract on PubMed
Practical Takeaways
- •Testicular volume equations significantly affect predicted sperm output; use actual DSO data when available for breeding management decisions rather than relying solely on morphometric predictions
- •Daily semen collection does not impair sexual behavior or sperm quality in healthy jacks, supporting the feasibility of intensive collection protocols for breeding programs
- •Donkey jacks demonstrate high reproductive efficiency with considerable individual variation; breeding performance should be assessed on individual animal basis rather than breed averages
Key Findings
- •Average daily sperm output was 9.1 ± 4.1 billion sperm in Dezhou donkey jacks, with predicted DSO ranging from 4.7 to 18 billion depending on testicular volume calculation method
- •Spermatogenic efficiency varied from 50 to 150% across jacks, indicating clinically normal donkeys can exceed predicted sperm output based on testis size
- •Sexual behavior and sperm motility remained consistent across 10 consecutive daily collections, demonstrating no adverse effects from repeated semen collection
- •Jack semen could produce 15-47 inseminating doses for on-site breeding (300-500 million progressively motile sperm/dose) or 4-14 doses for cooled-shipped semen (1 billion sperm/dose)