Abstract

Abstract. The purpose of the research was to assess the duration of the length of productive life of Simmental cows. Methods. The research was carried out on Simmental cows bred in 14 regions of the Russian Federation, the total livestock was 8 832 heads. The calculation of the heritability coefficients and correlation (genetic and paratypic) was carried out by using the programs RENUMF90 and REMLF90. Results. A fairly strong relationship was established between the duration of a productive life (months) and the age of culling (lactations) r = +0.795, the length of productive life (months) and lifetime productivity within the range of +0.669…+0.714. However, the relationship between the age of culling (lactations) and lifetime productivity is moderate, from +0.261 to +0.316. A moderate negative relationship was obtained between the age of culling (lactations) and milk yield per first lactation from –0.472 to –0.486. The average relationship was found between milk yield per first lactation and lifetime productivity from +0.567 to +0.588. Cows of the Altai Territory (3.08 lactations or 61.6 months), the Republic of Mordovia (3.38 lactations or 62.4 months) and the Lipetsk region (3.40 lactations or 65.7 months) were distinguished by low age of culling. While the greatest length of productive life was noted in animals and Bryansk (5.48 lactations or 86.9 months) and Irkutsk regions (4.57 lactations or 77.1 months). Bryansk (23 630 kg of milk), Tyumen (18 156 kg) and Irkutsk (17 751 kg) regions occupied the leading positions in lifetime productivity of cows in the sample, while the outsiders were the regions of traditional cattle breeding - Altai Territory (12658 kg of milk), the Republic of Bashkiria (12 482 kg). Scientific novelty. For the population Simmental cattle of the Russian Federation, for the first time, an assessment of selection and genetic parameters of lifelong productivity and length of productive life of Simmental cows was carried out, depending on the breeding region.

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