A retrospective study of artificial insemination of 251 mares using chilled and fixed time frozen-thawed semen.
Authors: Crowe C A M, Ravenhill P J, Hepburn R J, Shepherd C H
Journal: Equine veterinary journal
Summary
# Artificial Insemination in Mares: Chilled versus Frozen Semen Frozen semen has traditionally been viewed as an inferior and more demanding option compared to chilled semen for equine artificial insemination, yet limited direct evidence supports this perception. Crowe and colleagues conducted a two-season retrospective analysis of 251 mares bred using fixed-time insemination protocols to directly compare conception rates between the two semen types. Conception rates proved comparable between groups, challenging the long-held assumption that frozen semen substantially compromises fertility outcomes. For practitioners, this finding suggests that the choice between chilled and frozen semen need not be driven by concerns over success rates alone; instead, decisions can be based on logistical factors such as storage duration, transport requirements, and breeding timeline flexibility. These results may encourage wider adoption of frozen semen protocols where circumstances favour their use, particularly for mares requiring breeding at specific intervals or where chilled semen availability is limited.
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Practical Takeaways
- •Frozen semen may be a viable alternative to chilled semen for breeding programmes when considering both conception rates and management practicality
- •Fixed-time insemination protocols appear applicable to both semen types, potentially simplifying breeding management logistics
- •Practitioners should reconsider assumptions about frozen semen efficacy, as this study suggests performance may be comparable to chilled semen
Key Findings
- •Retrospective comparison of conception rates between chilled and frozen semen in mares over 2 breeding seasons using fixed-time insemination protocols
- •Study challenges historical perception that frozen semen has poorer success rates compared to chilled semen
- •Examined labour intensity and practical outcomes of both semen preservation methods in equine reproduction