Population-genetic parameters of the Romanov sheep breed in the aspect of control and management of selection processes

The main goal of breeders today is the breeding of animals that provide the most efficient and profitable production. The paper presents the results of the assessment of the influence of genetic and paratypic factors on the main economically significant features of the Romanov sheep breed bred in the Yaroslavl Oblast. It was found that the controlled signs are largely due to the influence of genetic factors - the effects were 71.6% by live weight and 74.4% by fertility at the first lambing. In particular, the live mass of the proband is significantly influenced by the effects of the herd, the live mass of the father, the live mass of the mother and the effect of the tribe; fertility is influenced by the effects of the herd, the live mass of the mother, the type of birth of the mother and the level of the breeding nucleus. The monitoring of population-genetic parameters of productive traits of the Romanov sheep breed has shown that the group of fathers of probands with low genetic and average phenotypic variability in live weight is characterized as a good genetic material. Further improvement is possible in the selection of the best individuals and the allocation of new genealogical structures. Evaluation of the maternal basis for fertility has shown that at a high phenotypic and low genetic variability, the effect of selection can be increased by regulating environmental conditions that have real effects at the level of 25.6% with the effect of the mother’s birth type of 22.6%. High genetic and low phenotypic variability for live weight inthe herd in the first and the last lambing has been revealed. With high phenotypic variability in fertility, the heritability of the trait is low. Therefore, the effect of selection can be increased by regulating environmental conditions. The obtained parameters can be used with high reliability in breeding modeling, in particular, in the development of genotype assessment models.