Pregnancy rates in mares after a single fixed time hysteroscopic insemination of low numbers of frozen-thawed spermatozoa onto the uterotubal junction.
Authors: Morris L H A, Tiplady C, Allen W R
Journal: Equine veterinary journal
Summary
# Editorial Summary Conventional frozen semen protocols demand repeated ultrasound monitoring to inseminate mares within 6–12 hours of ovulation, requiring 300–500 million spermatozoa per dose—a threshold that proves prohibitively high for emerging reproductive technologies like sex-sorted semen, which typically yield only 5–20 million viable cells per straw. Morris and colleagues investigated whether hysteroscopic deposition of low-dose frozen-thawed semen directly onto the uterotubal junction could maintain pregnancy rates whilst bypassing these conventional requirements, using a fixed-time insemination protocol that eliminated the need for intensive ovulation monitoring. The team achieved pregnancy rates comparable to standard protocols despite using substantially fewer spermatozoa, demonstrating that precise anatomical placement of thawed semen can offset the reduced numbers available from emerging technologies. This approach has important implications for practitioners seeking to utilise sex-sorted or otherwise limited-quantity semen, as it potentially removes both the logistics burden of frequent ultrasonography and the economic barrier of high sperm doses. For breeding programmes targeting specific traits via sex-sorting or other specialised semen processing, hysteroscopic insemination warrants consideration as a viable alternative to conventional breeding schedules.
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Practical Takeaways
- •Hysteroscopic insemination technique allows use of sex-sorted semen and other limited-availability semen products by reducing sperm number requirements from 300-500 × 10⁶ to 5-20 × 10⁶
- •Single fixed-time insemination protocol reduces labor costs and management intensity compared to repeated ultrasound monitoring for ovulation timing
- •This technique may improve fertility outcomes in stallions with poor semen freezability or limited frozen reserves
Key Findings
- •Hysteroscopic insemination directly onto the uterotubal junction enables pregnancy achievement with significantly lower frozen-thawed sperm numbers than conventional practice
- •Single fixed-time insemination synchronized to ovulation can be effective, reducing need for repeated ultrasonography monitoring
- •Low sperm numbers (5-20 × 10⁶) may be viable for breeding when deposited at optimal anatomical location