The studies were conducted to determine the effectiveness of selection of cows of a desired body type on the basis of a linear assessment of the exterior. The novelty of the research lies in the fact that the system of linear evaluation of the exterior of cows was tested in modern dairy cattle populations and the effi ciency of selection by a desired body type was revealed. The exterior of cows of the fi rst calving of 145 Ayrshire and 305 black-and-white breeds in breeding farms of the Vologda Oblast was linearly evaluated. The theoretical and methodological basis of the
study comprises works of domestic and foreign scientists. We used general scientifi c research methods, such as monographic, statistical, tabular methods of data visualization. The work identifi es that the studied populations of Ayrshire and black-and-white breed consist mainly of animals with well-expressed dairy forms – 6.8 and 6.7 points, respectively. Cows have a large udder, fi rmly attached to the trunk (6.2 points), with developed fore (5.7 and 6.1 points) and rear udders (6.7 and 6.9). The category “Excellent” was characteristic of 83.4% of animals in
the Ayrshire breed and 71.8% in the black-and-white breed. A positive correlation of milk yield for 100 days of the fi rst lactation with the length of the anterior lobes (r = 0.26 – 0.32) and the width of the posterior lobes (r = 0.30 – 0.41) of the udder was revealed, with a high degree of reliability (P ≤ 0.001). The average yield of the cow group with the category “Excellent” is higher than that of the group of animals with the category “Good plus”, by 7.7% for the Ayrshire breed and by 10.4% for the black-and-white breed. The selection of cows of desirable type of exterior
will improve exterior features and increase productivity of the herd. The linear assessment of the exterior of animals in breeding farms should be carried out constantly, with the acquisition of cows of the fi rst calving. Further research on the type of animal physique will be conducted to determine the development trend of the constitution of dairy breeds cattle
Keywords
effi ciency, body type, exterior, linear estimation, complex of features, dairy breeds