Economically useful traits of cows depending from the various dates of their first insemination

Abstract

In Sverdlovsk region Holsteinized black-and-white cattle of the Ural type are being bred. This type of cattle is represented by numerous, highly productive animals with a high genetic potential for productivity. The aim of this article is to study the correlation of age of the first insemination of heifers on their economically useful traits. It was found that the age of the first insemination directly affects the milk productivity of Holsteinized black-and-white cattle of Ural type. The difference in age of the first insemination between the groups was 2.7 months, or 18.6%. The difference of productive period longevity between the groups was also observed, which was 0.21 of lactation (6.7%) in favor of the group that got its first insemination at age of 16-18 months. Cows inseminated for the first time at an earlier date featured lower parameters of milk productivity: lower milk yield for life, lower milk yield for the first lactation and for maximum lactation. The difference was significant at P≤0.01 in favor of cows which underwent the first insemination at age of 16-18 months for life-long milk yield. A significant difference in MFP in milk was revealed in favor of the cows in the first group (the period of the first insemination was 14-15 months). It was 0.09% at P≤0.01. The difference in MFP in milk did not have a considerable influence on increase of nutrients yield in milk, in particular milk protein. The duration of the period between calvings and the service period was long in both groups of cows, which allows concluding that, regardless of the age of first insemination, the decrease in reproductive capacity in cows of modern Holsteinized black-and-white cattle is observed. This is proved by the record KVS – 0.87 - 0.88.