Variability of indicators of milk productivity in cows of different genotypes and with different index of lactation constancy

at present, the livestock industry in Russia is aimed at obtaining highly productive cows, taking into account their individual characteristics. It is known that animals with high genetic potential react to certain environmental changes especially. Hence, phenotypic evaluation will not help select the best cows with high genetic potential. Therefore, the assessment of individual qualities requires a new approach, which can be safely attributed to various kinds of indices, among which the index of lactation constancy occupies a special place. Such an index score fully characterizes the genotype. Any herd is characterized by a large genetic diversity of individuals. The variability of milk productivity traits determines this diversity, therefore, among highly productive cows there are those that are able to maintain the amount of milk yield and other valuable traits and be able to pass them on to their descendants. The main goal of breeding is aimed at identifying cows with such a valuable genotype and further their widespread use within the farm. Cows, daughters of different breeding bulls with a high index of lactation constancy, can serve as a starting point in the selection of producers with further recommendation for their use in different populations with different levels of productivity.