Dynamics of the live weight of replacement heifers depending on their origin from the sire

Abstract

In the last few decades the improvement of domestic dairy cattle was due to the widespread use of the gene pool of the best world breed such as Holstein. As a result of crossbreeding the breeding stock of the domestic Black-and-White breed with the sires of Holstein breed in different regions of the country a population of crossbreds has been created. The purpose of the work was to study the age dynamics of the live weight of replacement heifers depending on the paternal origin and the correlation between the indicators for the growth periods. The daughters of different sires have a difference in their live weight at the first insemination. The live weight of more than 400 kg was obtained from replacement heifers obtained from the sires Saber, Decaro and Baquero. The daughters of the sires Gatedenser, Bentley and Alta Ciara in live weight were inferior to their herdmates by 2,7–9,3 kg or by 0,7–2,8 % (P ≥ 0,05). The bulk of the replacement heifers are inseminated at the age of 13 months and only the daughters of the sire Alta Ciara are inseminated at the age of 14,1 months with a live weight of 396,7 kg. Despite the almost identical live weight of heifers at birth they differed from each other in the process of rearing. It has been established that the live weight at birth is not an indicator for assessing the further growth of replacement young animals. At 6 months of age the correlation of live weight at the age of 6 months and at the first insemination was positive and ranges from 0,01 (daughters of the sire Baquero) to 0,55 (daughters of the sire Decaro). Selection of heifers at the age of 6 months by their live weight allows us to choose the best and provide the opportunity to inseminate them at the age of 12–13 months with the organization of intensive rearing.