Effect of Timing of Postovulatory Insemination Relative to Human Chorionic Gonadotropin/Buserelin Treatment With 1 Straw of Frozen-Thawed Semen on Mare Fertility.
Authors: Immonen Isa, Cuervo-Arango Juan
Journal: Journal of equine veterinary science
Summary
# Editorial Summary Managing mares for frozen semen insemination demands significant time and expense, particularly when attempting to time artificial insemination precisely around ovulation. This retrospective analysis examined whether the interval between pre-ovulation ultrasound checks affected conception rates and early embryonic loss in mares receiving a single straw of frozen-thawed semen after ovulation had already occurred, whilst also comparing the efficacy of human chorionic gonadotropin (hCG) versus buserelin for inducing ovulation. Pregnancy rates remained consistent across different monitoring intervals—ranging from 26.1% to 34.5%—with embryonic loss rates similarly unaffected whether mares were checked every 4, 8, or 16 hours post-hormone administration; neither the ovulation-inducing agent, cycle number, nor individual stallion influenced these outcomes. For practitioners, these findings suggest that intensive overnight monitoring protocols offer no fertility advantage when implementing postovulatory insemination with frozen semen, permitting more pragmatic breeding schedules and potentially reducing labour-intensive supervision without compromising reproductive success.
Read the full abstract on PubMed
Practical Takeaways
- •Veterinarians can reduce labor costs and frequency of late-night examinations when managing mares for frozen semen AI with ovulation-inducing drugs, without compromising pregnancy rates
- •Either hCG or buserelin can be reliably used for ovulation induction; drug choice does not significantly impact fertility outcomes with postovulatory breeding
- •Single-straw frozen semen protocols can be successful even with less frequent ovulation monitoring, making breeding programs more practical and economical
Key Findings
- •Interval between ovulation checks (4, 8, or 16 hours) had no significant effect on pregnancy rates (26.1–34.5%) or embryonic loss rates (0–13.3%)
- •Both human chorionic gonadotropin and buserelin were similarly efficacious for ovulation induction in postovulatory AI protocols
- •Single straw frozen-thawed semen produced viable pregnancies regardless of examination interval timing
- •No advantage to frequent evening and night-time ovulation checks when using postovulatory AI with ovulation-inducing drugs