Comprehensive estimation of the genotype of the Romanov sheep breed in managing the selection process of breeding herds

The aim of the work is to estimate of the genotype of the Romanov sheep breed by a set of features to predict the animals’ breeding qualities, the expected genetic improvement by economically significant features in micropopulations, to determine the projected economic effect of the selection index use. For the first time, an improved method for assessing the Romanov sheep’s genotype is proposed, taking into account the indicators of multiplicity and meat productivity. Variational-statistical, correlative-regression and variance-covariance methods of data processing were used in the work. Significant valid differences between the herds in the dams’ live weight in the first lambing and fertility were established, necessitating an individual approach to the construction of the index in each particular herd. The level of heritability of the studied indicators is included in the low and medium boundaries, varying between 0.293-0.335 in live weight and 0.121-0.184 in fertility on the farms. In the controlled flocks of the Romanov sheep, a fairly high positive phenotypic and genotypic dependence between the indicators of live weight and fertility for the studied features was revealed. The indices were in the range of 0.487-0.549 for phenotypic and 0.491-0.581 for genotypic correlation coefficient. This suggests that the use of these features in one model of the selection index will allow to conduct a reliable assessment and effective selection simultaneously for both features. The accuracy of genotype estimation using the proposed model for all herds exceeded 0.400. Consequently, the index can be used to estimate sheep genotype and breeding selection. It was found that using the proposed selection index, the expected genetic effect on the live weight at first lambing will be from 0.591 to 1.356 kg per head per year, the expected yield of lambs will increase by 0.036-0.045 lambs per dam sheep per year. The economic effect from the model use will make up to +51,08 thousand RUB from lamb meat sales and +18,60 thousand RUB from breeding young animals’ sales.