Methodological approaches to phenotype and breeding value assessment of horses based on their performance in dressage: a case study of the Russian Riding breed
Abstract
In sport horse breeding under conditions of a limited gene pool and geopolitical changes, the intensification of selection and obtaining an objective assessment of phenotypes and breeding values based on horses’ performance have become especially important. Traditional approaches based on highest lifetime achievement don’t take into account the number of starts and age-related characteristics, which leads to biased estimations. The aim of the study was to develop methodological approaches for assessing of phenotype and breeding value of horses by their own performance in sport, using the Russian Riding breed in dressage as a case study. The material consists of the competition results of all Russian Riding horses in dressage from 2010 to 2025. To assess the phenotype used the corrected transformed rank for the season (KTR), the sum of KTR, the Smoothed indicator R, and standardized phenotype assessment (SPA), calculated from average KTR using group means and standard deviations. Breeding value was estimated using the best linear unbiased prediction (BLUP) method, Animal Model. The shrinkage parameter k were established for the Smoothed indicator R of the Russian Riding horses in dressage. Rank correlations between different indicators were determined, simplified SPA formulas and a calibration of the (grading) bonitation scale were proposed. It was shown that the Smoothed indicator R agrees well with EBV and can be used as a phenotypic alternative to BLUP for assessing horses’ performance. The SPA (standardized phenotype assessment) can be used as a simplified assessment tool when start data are unavailable. The results indicate that the proposed approach is suitable for the practical evaluation of horses’ performance in sport horse breeding, as well as for ranking animals when the data required for full-scale genetic calculations are insufficient.