Interspecific and Intraspecific Artificial Insemination in Domestic Equids.
Authors: Fanelli Diana, Moroni Rebecca, Bocci Carlotta, Camillo Francesco, Rota Alessandra, Panzani Duccio
Journal: Animals : an open access journal from MDPI
Summary
# Editorial Summary: Interspecific and Intraspecific Artificial Insemination in Domestic Equids Reproductive outcomes differ markedly between horses and donkeys despite their ability to interbreed, prompting Fanelli and colleagues to investigate pregnancy rates following artificial insemination (AI) in both species using semen from stallions and jackasses of proven fertility. The research involved eight Standardbred mares and nine Amiata jennies, with pregnancy diagnosis beginning on day 10 post-ovulation and continuing daily until embryo detection or day 16. Mares achieved substantially higher pregnancy rates regardless of sire species (66.7%, 20/30 inseminations), whilst jennies managed only 27.1% (19/70), representing a significant biological difference between the two females. Intraspecific breeding proved considerably more successful overall at 67.6% (25/37), compared with interspecific crosses at 22.2% (14/63), with hinny production (jennies bred to horse stallions) yielding the poorest results at 16.3% (8/49), despite no observable differences in embryo diameter, developmental timing, or morphological quality between groups. These findings highlight that the domestic equid female phenotype—particularly in donkeys—presents fundamental barriers to successful crossing that warrant further investigation into reproductive physiology, and practitioners involved in hybrid breeding programmes should anticipate substantially reduced conception rates when pursuing interspecific matings, particularly from the donkey dam perspective.
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Practical Takeaways
- •Practitioners should expect substantially lower conception rates when performing interspecific AI in equids compared to intraspecific breeding, particularly when using horse semen in donkey females
- •Horse mares are significantly more receptive to AI than donkey jennies, regardless of semen source, making donkey breeding programs more challenging
- •If producing hinny hybrids is the goal, be prepared for very low pregnancy rates (16.3%) and consider alternative breeding strategies or veterinary consultation
Key Findings
- •Pregnancy rates in horse mares (66.7%) were significantly higher than in donkey jennies (27.1%) regardless of sire species (p < 0.05)
- •Intraspecific AI achieved 67.6% pregnancy rate compared to 22.2% for interspecific AI (p = 0.0001)
- •Jennies inseminated with horse stallion semen showed the lowest pregnancy rate at 16.3%, suggesting reproductive incompatibility in hinny production
- •Sire species (horse vs donkey) did not significantly affect pregnancy rates, indicating the female genotype is the primary determinant of success