Plasticity effect of rider-horse interaction on genetic evaluations for Show Jumping discipline in sport horses.

The research article explores the impact of rider-horse interaction (RHI) on genetic evaluations for Show Jumping discipline in sport horses, with models incorporating RHI proving better fitting than others. The study used sports results from 1,101 Spanish Sport Horses to examine distinct age-based patterns in genetic variance and heritability.

Research Methodology

• The study used 31,129 sport results from 1,101 Spanish Sport Horses who had been ridden by 606 different riders.
• Only riders who had ridden more than one horse and horses ridden by more than one rider were taken into account for the analysis, making the study focus solely on multiple interactions.
• Horses were grouped into three age levels to understand how RHI and its effects differed by the age of the horse.
• Data was then modeled and analyzed with five different linear models, each evaluating different random effects and factors.

Models and Analysis

• The five linear models varied according to the covariates, the homogeneity/heterogeneity of RHI, and the relative residual random effects.
• The aim was to select the most fitting model for the genetic evaluation of the sport horses based on the data.
• Models incorporating the RHI effect (M2, M4 and M5) fitted better than those that did not consider this interaction.
• The best fit was obtained for model M4 which accounted for heterogeneous residual variance.

Findings

• The study found a steady increase in genetic variance with age, while heritability revealed a response on three intervals.
• Analysis revealed different “plastic abilities” or flexibility within the rider-horse relationship over time, indicating how the RHI can evolve with age.
• The study highlights the importance of considering RHI in genetic evaluations for Show Jumping discipline in sport horses as it significantly influences performance.
• This research extends the understanding of RHI and how it can be used to improve breeding and training strategies for sport horses.