Equine

Distance and type of race: different traits for racing performance in Thoroughbred horses?

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Abstract

This study aimed to estimate genetic parameters of racing performance and characterize genetically the diversity of careers in flat horse racing. Racing records from 2000 to 2024 included 1,081,036 performances achieved by 93,609 French thoroughbred horses, over 101,882 flat races. Racing performance was defined as the logarithm of earnings (LE) for each race and each horse - real or simulated by halving the amount for each successive rank for the non-winning horses - and start status over the career (binary variable). Performance was first broken down by race type (stakes races including listed and group races, conditions races, handicap races and claiming races) then by race distance (short under 1600m, intermediate, long above 2400m). Of 93,609 horses, 17% participated in at least one stakes race, 41% in a handicap race, 45% in a claiming race, and 90% in a conditions race. Additionally, 43% raced at short distances, 88% at intermediate distances, and 34% at long distances. A multi-trait animal model with LE as linear trait and start status as threshold trait was considered. Fixed effects included age, stall number (both for LE only), combination of sex, year and country of birth, and inbreeding coefficient (mean: 1.981%, sd: 1.247%), calculated using whole pedigree and divided into 8 levels. Random effects included trainer (n=3,532), animal additive genetic value with 180,207 horses in pedigree, and permanent environment effect. Analysis was performed by Markov chain Monte Carlo Gibbs sampling using the TM software. Inbreeding coefficient had a negative effect on LE but a variable effect on start status. For stakes races, the estimated effects of inbreeding on LE and start status were respectively -0.09 and -0.01 in phenotypic standard deviation unit for the level >5.0% compared to the level [0.0%-0.5%]. Trainer effect accounted for 2 to 18% of total variance for start status and 1 to 8% for LE. For LE, heritability estimates were 0.132 (se 0.004), 0.150 (se 0.001), 0.091 (se 0.002) and 0.068 (se 0.002) respectively for stakes, conditions, claiming and handicap races, whereas they were 0.293 (se 0.004), 0.380 (se 0.006), 0.371 (se 0.003) and 0.329 (se 0.007) for start status. Repeatability of LE ranged from 0.156 (se 0.001) to 0.336 (se 0.001). Genetic correlations among LE ranged from 0.699 (se 0.013) to 0.933 (se 0.007) whereas genetic correlations among start status ranged from -0.510 (se 0.015) (stakes/conditions races) to 0.392 (se 0.017) (handicap/claiming races). Regarding race distance, results revealed a strong negative genetic correlation (-0.734, se 0.004) between participation in short- and long-distance races. Main results enabled us to conclude that participation in different types of races or distance is heritable and genetically different, but success in these different race types or distances are very similar traits.

Keywords: 2026

How to Cite:

Harari, S., Théry, A., Fortier, G. & Ricard, A., (2026) “Distance and type of race: different traits for racing performance in Thoroughbred horses?”, World Congress on Genetics Applied to Livestock Production Digital Archive 2026(1): 2268120. doi: https://doi.org/10.31274/wcgalp.23400

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