Linear affiliation influence on longevity and dairy productivity of cows

The purpose of research is to study the milk productivity of cows and the period of economic use in connection with their linear affiliation. Objectives: to establish the productivity of the cows of the herd in connection with their age in calving and linear affiliation. The experiment was conducted at ZAO (closed joint stock company) Plemkhoz Naro-Osanovsky, Moscow Region, from 2020 to 2021. The object of the study was Holstein cows (n = 56 heads) from the first to the sixth lactation (Reflection Sovering line - 36 heads, Vis Back line Idial - 15 goals, Pabst Governer line - 5 goals). The studied indicators: milk yield for 305 days of lactation, mass fraction of fat and protein in milk, duration of economic use. Primary data for the study were taken from the database of the IAS SELEKS - Dairy Cattle. The received data were processed biometrically. In the structure of the herd, the share of animals belonging to the Reflection Sovering line (2nd group) is 52.78 %, the Vis Back Idial line (1st group) - 38.19, the Pabst Governer line (3rd group) - 5.56, others - 3.47 %. Milk productivity increases up to the fourth lactation by an average of 27.39 %. The longest period of economic use in cows of the 1st group is 6 lactations, which is more than in cows of the 2nd and 3rd groups by 0.2 and 0.46 lactations, respectively. In cows of the 1st group, the indicators of milk productivity are 5.3 % higher in comparison with cows of the 2nd group, and with the indicators of cows of the 3rd group - by 33.8 %. In cows of the 2nd group, on average, the mass fraction of fat is higher than in the sample by an average of 0.06 %. At the same time, the maximum indicator - for the first lactation (4.36 %), exceeds the indicators: for the sample by 0.18 %, cows of the 3rd group by 0.26 % (P = 0.95). The maximum indicators of the content of the mass fraction of protein in cows of the 2nd and 3rd groups relative to the average for the sample are higher by 0.08 and 0.07 %, respectively. According to the totality of the studied economically useful traits of cows, the maximum number of indicators is higher than the average for the sample in cows of the Reflection Sovering and Vis Back Ideal lines, which must be used for further breeding work.