Correlation of performance traits of black-and-white first- calves

Abstract

The long-term use of Holstein breeding bulls of foreign selection has led to the creation of a large quantity of Holsteinzed cattle in various climatic and ecological forage zones of the country, which also differs in their economically useful traits and biological features inherited from the breed resources of cattle in the breeding zone and the country of origin of the breeding bulls involved in crossing. In Sverdlovsk region the Holsteinzed black-and-white cattle of the Ural type are being bred, which are represented by large highly productive animals with a high genetic potential for milk productivity. The aim of the work is to study the correlation of productive qualities parameters among first-calves of black-and-white cattle. There is no difference between the breed lines in their productivity or they are so insignificant that they prove the uniformity of the bred livestock. This uniformity is achieved by strict selection and constant observance of the same type of selection applied for breeding bulls to serve in the herd. An insignificant difference in milk productivity parameters of cows of different Holstein lines is caused to the high level of inbreeding in the herd. The inbred animals account for up to 65 percent or more, depending on the age. A low positive correlation between the live weight of cows and their productive qualities is established, which practically has no dependence on the linear origin of cows.