Practical protocols for timed artificial insemination of jennies using cooled or frozen donkey semen.
Authors: Yang Feng, Li Nan, Liu Bing, Yu Jie, Wu Shuaishuai, Zhang Ruitao, Yang Weigang, Ji Chuanliang, Sun Qianqian, Ma Jinliang, Li Min, Zhou Jingqian, Zhou Xiangshan, Pietrani Melina, Losinno Luis, Zeng Shenming
Journal: Equine veterinary journal
Summary
# Timed Artificial Insemination in Donkeys: Practical Protocols for Cooled and Frozen Semen The expanding donkey breeding industry has created demand for reliable timed artificial insemination (TAI) protocols, yet these remain poorly characterised in jennies compared to equine species. Researchers developed and tested TAI strategies centred on GnRH analogue (deslorelin) ovulation induction, establishing optimal dosing, follicle diameter thresholds, and insemination timing across three experimental phases involving over 300 animals. A 2.2 mg deslorelin dose reliably induced ovulation (≥90% within 48 hours), with peak ovulation rates occurring between 32–48 hours post-treatment when follicles measured 31–35 mm at induction; single inseminations with cooled semen at 8 hours achieved a 49.2% pregnancy rate, whilst double inseminations with frozen semen at 34 and 42 hours post-induction yielded acceptable results (28–35% pregnancy rates) even at lower sperm doses (1 × 10⁸ motile spermatozoa per cycle). For practitioners, this work provides evidence-based timing recommendations that can substantially improve reproductive efficiency in donkey breeding programmes, though the absence of control groups and the 22.5% failure rate in ovulation synchronisation warrant consideration when implementing these protocols in individual studs.
Read the full abstract on PubMed
Practical Takeaways
- •Use 2.2 mg deslorelin for ovulation induction in jennies when follicle diameter is 31-35 mm; expect ovulation between 32-48 hours with peak occurrence at 36-38 hours
- •Cooled semen provides superior pregnancy rates (49.2%) with single insemination at 8 hours, making it preferable to frozen semen protocols when available
- •Frozen semen TAI requires two inseminations (34 and 42 hours post-induction) and produces lower but acceptable pregnancy rates; using minimal effective sperm dose (1×10⁸ motile spermatozoa) reduces costs without compromising fertility
Key Findings
- •Deslorelin 2.2 mg achieved ≥90% ovulation within 48 hours of treatment in jennies
- •Optimal follicle diameter for ovulation induction was 31-35 mm, with 70% of ovulations occurring 32-48 hours post-induction and peak incidence at 36-38 hours
- •Single TAI with cooled semen at 8 hours post-induction achieved 49.2% pregnancy rate (29/59 jennies)
- •Double TAI with frozen semen at 34 and 42 hours post-induction achieved 28.8-35.5% pregnancy rates across different sperm doses (1-10 straws per cycle), with acceptable results using 1×10⁸ motile spermatozoa per cycle