Sex-Related Differences in Show-Jumping Performance of Retired Thoroughbred Racehorses in Relation to the Interval Since Race Retirement.
Abstract: To investigate the factors affecting the utilization of retired Thoroughbred racehorses in equestrian disciplines, Bayesian linear mixed models were separately fitted using rank, round time, and obstacle faults from show-jumping competitions restricted to retired Thoroughbred racehorses as dependent variables, with the interaction between horse sex and the interval from race retirement to competition (as a proxy for transition training to show-jumping) as a fixed effect. When the interval was short (≤1 year), the estimated marginal mean of rank was statistically significantly lower in stallions (0.26) than in mares (0.41) and geldings (0.39). However, ranking improved with longer intervals in all sexes, with the greatest improvement observed in stallions, and the significant sex-related differences disappeared at the 3-year interval, suggesting an effect of transition training on ranking. Round time improved significantly with longer intervals in all sexes, consistent with the ranking pattern; significant improvement in obstacle faults was observed only in stallions and geldings. The explanatory power of the models, including major random effects, rider, horse ability, sire and affiliation after retirement, was moderate (conditional R: 0.40-0.65), whereas that of the fixed effects was small (marginal R: 0.02-0.07), indicating the multifactorial nature of success in competition.
Publication Date: 2026-02-11 PubMed ID: 41751023PubMed Central: PMC12937418DOI: 10.3390/ani16040562Google Scholar: Lookup
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Summary
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Overview
- This study examines how the time since retirement from racing and the horse’s sex influence the performance of retired Thoroughbred racehorses in show-jumping competitions.
- It focuses on analyzing ranks, round times, and obstacle faults to understand the impact of transition training on different sexes.
Objective and Context
- The research aims to understand what factors affect the successful use of retired Thoroughbred racehorses in equestrian disciplines, specifically show jumping.
- Thoroughbred racehorses often retire from racing and transition to other equestrian sports, but performance variation among horses and between sexes is not well understood.
- The study uses the interval from race retirement to competition as a proxy for the duration of transition training into show jumping.
Methodology
- Bayesian linear mixed models were used for the statistical analysis, suitable for handling multiple sources of variability and uncertainty.
- Three dependent variables related to show-jumping performance were analyzed:
- Rank in competitions
- Round time (time taken to complete the course)
- Obstacle faults (errors such as knocking down rails or refusals)
- Horse sex (stallions, mares, geldings) and the interval since retirement were considered fixed effects, specifically their interaction.
- Random effects included rider, horse ability, sire (genetics), and affiliation (organizational or training group after retirement), capturing other sources of variability.
Key Findings
- Performance shortly after retirement (≤1 year):
- Stallions had a significantly lower mean rank (better performance) compared to mares and geldings.
- Lower rank value means a higher (better) position in competition, so initially stallions performed better.
- Effect of longer transition intervals:
- Ranking improved across all sexes with increasing time since retirement, indicating improvement due to transition training.
- The greatest improvement was seen in stallions, causing the initial sex-based difference to disappear by about 3 years post-retirement.
- Round times also improved significantly in all sexes, mirroring ranking improvements.
- Improvements in obstacle faults were significant only in stallions and geldings, not mares.
- Model explanatory power:
- The models’ conditional R squared values, measuring the amount of total variance explained by both fixed and random effects, ranged from 0.40 to 0.65 — indicating moderate explanatory power.
- The marginal R squared values, representing variance explained by fixed effects alone (sex, interval, and their interaction), were low (0.02–0.07), highlighting that fixed effects explained only a small part of performance variation.
- This suggests success in show jumping is influenced by many factors beyond just sex and time since retirement.
Interpretation and Implications
- Initial better performance by stallions could be related to their physical or behavioral traits at retirement or prior training.
- Improvement over time, especially for stallions, implies that longer transition training positively affects show-jumping performance and can equalize differences between sexes.
- The lack of significant improvement in obstacle faults for mares may suggest sex-related differences in adaptability or training response for certain skills.
- Random effects such as rider skill, individual horse ability, genetic factors, and post-retirement training affiliations play a substantial role in competitive outcomes.
- The multifactorial nature of success indicates that trainers and owners should consider comprehensive training, careful rider selection, and genetic factors for maximizing the show-jumping potential of retired racehorses.
- The study informs strategies for managing retired Thoroughbred racehorses in second careers and supports tailored training programs based on sex and transition duration.
Conclusion
- Time since retirement (proxy for transition training) and horse sex interact to influence show-jumping performance in retired Thoroughbreds.
- While stallions initially outperform others, longer training reduces sex differences, improving overall competition results.
- Performance depends on many factors beyond sex and training interval, emphasizing a holistic approach to preparing retired racehorses for new disciplines.
Cite This Article
APA
Naito M, Nishihata S, Amano T.
(2026).
Sex-Related Differences in Show-Jumping Performance of Retired Thoroughbred Racehorses in Relation to the Interval Since Race Retirement.
Animals (Basel), 16(4), 562.
https://doi.org/10.3390/ani16040562 Publication
Researcher Affiliations
- Laboratory of Animal Genetics, Graduate School of Dairy Science, Rakuno Gakuen University, 582 Midorimachi, Bunkyodai, Ebetsu 069-8501, Hokkaido, Japan.
- Laboratory of Animal Genetics, Department of Sustainable Agriculture, College of Agriculture, Food and Environment Sciences, Rakuno Gakuen University, 582 Midorimachi, Bunkyodai, Ebetsu 069-8501, Hokkaido, Japan.
- Laboratory of Animal Genetics, Graduate School of Dairy Science, Rakuno Gakuen University, 582 Midorimachi, Bunkyodai, Ebetsu 069-8501, Hokkaido, Japan.
- Laboratory of Animal Genetics, Department of Sustainable Agriculture, College of Agriculture, Food and Environment Sciences, Rakuno Gakuen University, 582 Midorimachi, Bunkyodai, Ebetsu 069-8501, Hokkaido, Japan.
Conflict of Interest Statement
The authors declare no conflicts of interest.
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