Journal of equine veterinary science · 2026
When genes meet money: Genotype-by-prize interaction in Quarter Horses.
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Santana M L, Bignardi A B
Аннотация
BACKGROUND: Barrel racing performance reflects a complex interplay among genetic merit, rider ability, training strategies, and competition-specific conditions. In practice, events differ substantially in their economic scale, and prize money can serve as a proxy for management intensity, rider expertise, and selection pressure.
AIMS/OBJECTIVES: This study investigated whether economic stratification, represented by total prize money per event, is associated with changes in (co)variance components for barrel racing time in Brazilian Quarter Horses.
METHODS: A reaction-norm model was implemented using 349,262 race records, with genetic, permanent environmental, and rider effects modeled as random regressions along a continuous prize-money gradient. Variance components and genetic parameters were estimated across the gradient, and heterogeneity was assessed by comparing variance trajectories and correlation structures between contrasting economic environments.
RESULTS: Additive genetic variance increased moderately along the gradient (7.78 to 8.46), whereas rider and permanent environmental variances showed more pronounced increases, particularly in high-prize events. Residual variance declined from approximately 17.36 to 10.19, indicating greater homogeneity under elite conditions. Heritability estimates ranged from 0.19 to 0.23 across the gradient. Genetic correlations between low- and high-prize environments remained high (>0.90), whereas rider and permanent environmental correlations decreased to ∼0.93-0.83, evidencing stronger environmental specificity of non-genetic effects. Rider effects accounted for up to 29% of phenotypic variance in high-prize classes.
CONCLUSION: Prize money effectively captures an environmental gradient influencing variance heterogeneity. However, performance plasticity across economic contexts is primarily driven by rider and management effects, with limited evidence of genotype re-ranking.
AIMS/OBJECTIVES: This study investigated whether economic stratification, represented by total prize money per event, is associated with changes in (co)variance components for barrel racing time in Brazilian Quarter Horses.
METHODS: A reaction-norm model was implemented using 349,262 race records, with genetic, permanent environmental, and rider effects modeled as random regressions along a continuous prize-money gradient. Variance components and genetic parameters were estimated across the gradient, and heterogeneity was assessed by comparing variance trajectories and correlation structures between contrasting economic environments.
RESULTS: Additive genetic variance increased moderately along the gradient (7.78 to 8.46), whereas rider and permanent environmental variances showed more pronounced increases, particularly in high-prize events. Residual variance declined from approximately 17.36 to 10.19, indicating greater homogeneity under elite conditions. Heritability estimates ranged from 0.19 to 0.23 across the gradient. Genetic correlations between low- and high-prize environments remained high (>0.90), whereas rider and permanent environmental correlations decreased to ∼0.93-0.83, evidencing stronger environmental specificity of non-genetic effects. Rider effects accounted for up to 29% of phenotypic variance in high-prize classes.
CONCLUSION: Prize money effectively captures an environmental gradient influencing variance heterogeneity. However, performance plasticity across economic contexts is primarily driven by rider and management effects, with limited evidence of genotype re-ranking.