Genetic parameter estimation of novel international show-jumping indicators in horses

Genetic improvement of show-jumping competition results has a clear breeding goal which is to produce horses that can repeatedly clear technically demanding courses at maximum height, resulting in placement results. However, how to achieve this, and thus how to accurately choose breeding candidates, is far from straightforward due to the heterogeneity of competition outcomes. In this study, we analyzed Fédération Équestre Internationale (FEI) competition records from 19,232 horses together with pedigree data to evaluate novel phenotypes suitable for international genetic evaluations. Traditional traits (maximum height jumped, total prize money won, number of competitions) were analyzed together with composite ratios (clear-round ratio and placement ratio), modeled both across career and within 5-cm FEI height categories (1.20-1.60 m). Using animal models and binomial threshold models in ASReml, we estimated heritability, repeatability, and genetic correlations. Maximum height achieved in career showed moderate heritability (h² = 0.22), while earnings and number of competitions displayed low heritability and modest repeatability. Composite ratios modeled over career had low heritability (h²obs = 0.02-0.08) and moderate repeatability, whereas analyses within height categories revealed substantially higher heritabilities (h²obs up to 0.59), especially in mid-level classes (1.35-1.45 m). Genetic correlations were high between adjacent heights, but weaker between the lowest and elite levels, suggesting partly distinct genetic determinants across competition classes. These findings indicate that FEI-restricted composite phenotypes, especially mid-height ratios, provide informative and heritable indicators for breeding programs.