Brief communication: Heritability estimates for performance traits in NZ thoroughbreds

Abstract

Heritability estimates for four race performance traits were derived from 120,350 race starts involving 11,167 horses across five racing seasons (2019/2020–2023/2024) in New Zealand. Animal, trainer and jockey were modelled as random effects with fixed effects of gender, year, racetrack, racetrack condition, race rating, weight, barrier draw, and horse age. Finishing position was most heritable (0.16 ± 0.004), followed by log of earnings (0.14 ± 0.004). Estimates for win and top three placings were 0.01 ± 0.001 and 0.06 ± 0.003. The fixed effects were significant (p < 0.001) for most traits. Strong correlations between animal breeding values were observed for log of earnings and, finishing position (-0.88), top three placing (+0.81) and win (+0.60). The results indicate that population improvement is possible, but may be slow.