Updated approaches to assessing breeding value in purebred arabian horses: evaluation of individual racing performance and sire progeny quality
Abstract
Improving the methodology for assessing the breeding value of horses based on racing performance is a relevant task in modern horse breeding. The aim of the study was to develop such a system for purebred Arabian horses based on the results of racetrack trials. The research material consisted of records from 3,690 starts of 621 horses from 2020 to 2024. Two key indicators based on the placing and the category (complexity) of the race were used to characterize performance: the R2024 rating and the Adjusted Transformed Rank (ATR). Statistical analysis included the calculation of correlations, repeatability, heritability (h²), as well as the assessment of the breeding value (BV) of horses and sires based on progeny quality, with the calculation of Absolute (ABV) and Relative (RBV) breeding value indices. An extremely high correlation was established between the R2024 and ATR indicators (r = 0.98). The ATR indicator demonstrated higher predictive reliability: the repeatability coefficient of results from two to three years of age was 0.24 compared to 0.16 for R2024. The heritability of racing performance was moderate: 0.18 for two-year-olds and 0.40 for three-year-olds. Based on the calculation of breeding value, statistically significant “improver” and “deteriorator” sires were identified. The effectiveness of early evaluation was confirmed: horses with low results at two years of age maintained low productivity at three years. The developed system allows for an objective assessment of the racing qualities of horses and the breeding potential of sires. The ATR indicator has been recognized as more preferable for use in breeding practice due to its stability and high repeatability. For integration into the existing grading system, it is recommended to develop a scale for converting ATR values into standard grading scores, taking into account age characteristics.