LINEAR ASSESSMENT OF HOLSTEIN COWS EXTERIOR UNDER CANADIAN METHODOLOGY

The aim of the study is to determine the cow exterior using the Canadian system assessment chart with an emphasis on the rear third of the animal’s body. The main body parts of Holstein dairy cows were measured. Six measurements were taken from 274 Holstein dairy cows on two dairy farms in the Irkutsk Region. The animals under study were divided into 4 groups based on the number of completed lactations: first, second, third, fourth and older lactations. The main attention was paid to the rear third of the animal’s body. The following were determined using conventional methods, by measuring control points on the animal’s body: height and width at the ischial tuberosities, thighs, hipbones, oblique length of the hindquarters, distance between the hip joint and hipbone, and between the hip joint and ischial tuberosity. These measurements were taken in centimeters and rounded to whole numbers. The following were calculated: sacrum inclination angle and horizontal and vertical position of the hip joint. The overall score was calculated based on the importance of each section of the score card in points. According to the data obtained, with the intensification of dairy cattle breeding, evolutionary changes occur in the exterior of Holstein dairy cattle. Against the background of increased milk productivity, an increase in body size, a decrease in the angle of inclination of the sacrum and a caudal shift in the position of the hip joint are observed, which in turn affects the structure of the reproductive tract. In dairy cattle breeding, focusing on productivity indicators, significant attention must be paid to other characteristics that affect the efficiency of the entire technological process of milk production. Many of these characteristics are associated with the exterior of cows, for example, body type, size and shape of the udder, body dimensions, etc. In modern conditions of application of industrial technologies, when carrying out targeted selection of animals for the production of agricultural products, it is necessary to take into account the parameters of the exterior of cattle, which is a necessary condition for the normal functioning of the entire organism, reproduction and prospects for economic use.