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Information × Registration Number 0225U004885, (0124U000920) , R & D reports Title To investigate the effectiveness of the selection of Simmental cows according to the duration of their use in the conditions of organic and conventional milk production popup.stage_title Дослідити ефективність селекції корів симентальської породи за тривалістю їх використання в умовах органічного та конвенційного виробництва молока Head Kochuk-Yashchenko Olexander Anatoliyovich, Кандидат сільськогосподарських наук Registration Date 22-12-2025 Organization Polissya Institute of Agriculture of the National Academy of Agrarian Sciences of Ukraine popup.description1 To establish the reasons for the culling of Simmental cows in organic and conventional herds, as well as to determine the share of the influence of genotypic and paratypic factors on indicators of their lifelong use popup.description2 A comparative analysis of lifetime performance traits in Simmental cows demonstrated significant intergroup differentiation driven by sire origin, line affiliation, and paratypical factors under organic and conventional milk production systems. Under organic conditions, sires had a statistically significant effect on lifespan, productive use, lactation duration, and number of lactations, indicating a high genetic determination of productive longevity. The best lifetime performance was recorded in daughters of the sires Incubus CZ 577790071 and Dollar Et CZ 120158021, which significantly (P<0.01–0.001) outperformed progeny of other sires. Under conventional management, pronounced differentiation was not observed; however, daughters of Mrak CZ 23411683 showed a tendency toward higher lifetime productivity, while progeny of Bavor and Morello had lower values. Phenotypic consolidation analysis revealed that under organic conditions, progeny of Dollar, Incubus, and Rumgo were the most consolidated for productive longevity traits, whereas under conventional conditions all sires showed negative consolidation coefficients. One-way ANOVA confirmed a substantial effect of sire origin on lifespan, productive use, and lactation duration under both production systems (31.9–39.1%), as well as on milk fat and protein content under organic management (P<0.001). Line affiliation significantly influenced lifetime traits in the organic herd, with cows of the Regio line showing the highest performance and those of the Horror line the lowest. The optimal age at first calving was 27–31 months in organic herds and 788–917 days under conventional conditions. The season of first calving had a stronger effect in organic production, where spring-calving cows exhibited superior lifetime efficiency Product Description popup.authors Kucher Dmytro M. Ivan N. Savchuk Serhii O. Leonets popup.nrat_date 2025-12-22 Close