A. P. Shevchuk, T. A. Knyazeva
All-Russian Research Institute of Animal Breeding, Lesnye Polyany settlement, Moscow region, Russia
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Volume 26 No. 9
Date of paper submission: 19.06.2026, date of review: 06.07.2026, date of acceptance: 20.07.2026.
Published: 09/30/2026
Abstract. The reliability of a selection index depends directly on the quality of the underlying herd-recording data and on the soundness of the traits chosen for its structure. The purpose of the study was to assess the quality and informativeness of economically important traits in red dairy cattle breeds in order to select indicators suitable for inclusion in a multi-trait selection index. Methodology and methods. The dataset comprised 43 987 records from 18 061 cows across 16 breeding farms (Selex Dairy Cattle herd-management information system; birth years 2011–2024; lactations one through five). Seventeen traits of milk production, reproduction, and udder health were subjected to descriptive statistical analysis, outlier detection by biological and statistical (Tukey fences) criteria, log-transformation for variance stabilisation, and Pearson correlation analysis; all processing was carried out in the R environment. Scientific novelty. For the first time in a red-breed population, an end-to-end audit of the structure and quality of primary herd-recording data was performed as a distinct stage preceding index construction, with quantification of the proportion of biologically implausible records for each trait and justification of trait selection by the criteria of informativeness and non-redundancy. Results. Reproductive traits and somatic cell count were found to exhibit pronounced positive (right) skewness (coefficient up to 2.48) and a high proportion of outliers, reaching 48 % for age at first conception; biological filtering reduced skewness to the 0.1–1.0 range. Production traits showed stable, near-normal distributions and mutual redundancy (r = 0.94…0.96), making it appropriate to include only one of them in the index. The near-perfect linear dependence between days open and calving interval (r = 0.997) precludes their simultaneous use. Somatic cell count and number of services showed weak associations with the other traits, which enhances their value as independent components of the index.
Keywords: selection index, red breeds, Red Steppe, dairy cattle, data quality, trait informativeness, reproductive performance, somatic cell count, biological filtering, correlation analysis, herd recording
Acknowledgements. This study was carried out within the framework of the state assignment of the Ministry of Agriculture of the Russian Federation (topic No. 082-00066-26-00 on 2026 from 26th January 2026).
For citation: Shevchuk A. P., Knyazeva T. A. Assessment of trait quality and informativeness for constructing a selection index in red dairy cattle breeds. Agrarian Bulletin of the Urals. 2026; 26 (09): С. 1769‒1782. https://doi.org/10.32417/1997-4868-2026-26-09-1769-1782 (In Russ.)
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