Dynamics of growth indicators of replacement heifers of different lines
The aim of the research was to study the influence of the origin of replacement heifers of the Ural type of black-and-white breed on their weight growth. For this, in one of the breeding reproducers of the Sverdlovsk region, heifers born in 2017 - 2018 were divided into groups according to their belonging to the line of Holstein breeding bulls - Reflection Sovering 198998, Montvik Chieftain 95679, Vis Back ID 1013415, since they represent the main livestock of the herd. data of zootechnical and pedigree registration of the Selex program, acts of monthly weighing. Growth indices were calculated - absolute, average daily and relative gain in live weight, coefficient of increase in live weight according to generally accepted methods. It was found that all heifers grew intensively, reaching live weight at the age of first insemination (12.75 - 12.91 months) from 356.0 (Montvik Chieftain's line) to 407.3 kg (Reflection Sovering line), and by 18 - month age - over 425 kg. The highest live weight values were found in Reflection Sovering heifers, and the lowest in the Montvik Chieftain line. The heifers of the Vis Back Aydiala line grew most intensively, which is confirmed by the higher relative growth rates both for the entire study period and in each individual period.