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Actuality of research data is in contribution rate of growth of genetic progress according to main economic traits in Ayshire populations at the cost of conducting correlative- regression analysis and study of influence factors, as a preparatory phase in development of selection index for selection of animal units into selected groups. Study sample of cow heifers (n=12821), which are offsprings of 232 servicing bulls from 13 farms, is modified to normal distribution with the help of R-studio program (on control of events, emergence, removal of empty and impossible values). Calculation and analysis of selective- genetic parameters of economic traits are conducted, and also impact assessment of genetic and paratypic factors on realization of economic traits of local cattle population of Ayshire breed in Leningrad region for the period from 2014 to 2018. Animal milk production was 6848 kg with fat mass percentage and protein 4,07 and 3,29 %. We established lowering of MOP duration and reproductivity coefficient and fertility index (RC and FI). Multiregressional model was formed including into formula percentage of fat, protein, live weight and service period. It was established that with fat increase for 1 % milk yield will decrease by 15,3 kg, but with increase of protein on the same value- for 107,8 kg of milk. The most accurate influence on studied economic traits had father factor (14,97 – 41,58% ***). Consequently, with the aim to achieve positive result in population development of Ayshire cattle it is necessary to use bulls, having high genetic potential of milk yield and reproductive qualities.

vestnik ulʹânovskoj gosudarstvennoj selʹskohozâjstvennoj akademii

SELECTIVE- GENETIC PARAMETERS AND EVALUATION OF PHENOTYPIC VARIATION ACCORDING TO THE RANGE OF ENVIRONMENTAL AND GENETIC FACTORS OF ECONOMIC TRAITS OF AYSIRE BREED COWS