The intensity of the gain of live weight of heifers of Black-and-White breed and hybrids with zebu

Abstract

The first factor in breeding highly productive herds, both in order and importance is the intensive rearing of replacement heifers. The widespread use of Holstein breed as the breeding resources in dairy cattle in Russia in order to improve the economically useful characteristics of cattle of different breeds leads to the leveling of genotypes and a decrease in the valuable qualities of domestic breeds, resistance to diseases, obtaining high-quality replacement young animals. Hybridization especially remote according to many scientists is the greatest factor of evolution and selection and so far the only reliable method of breeding hybrid organisms based on a combination of their useful traits A comparative characteristic of the intensity of the live weight gain of heifers of Black-and-White breed and in comparison with zebu-like hybrid herdmates has been presented in the article. It has been found that the intensity of the live weight gain of heifers obtained by crossbreeding with zebu-like hybrid sires was higher than that of heifers of the same age of Black-and-White breed from birth to 15 months of age. The average daily gain in live weight in zebu-like hybrid heifers from birth to 6 months of age averaged was 733 g, from birth to the age of 12 months it was 739 g and from birth to the age of first insemination it was 704 g. The live weight of hybrid heifers at the age of 15 months was 345,1 kg, which on average was more than that of heifers of the same age of Black-and-White breed. So, from birth to 6 months they were inferior to hybrid herdmates by 6,5 %, at the age of 12 months by 4,2 % and at the age of 15 months by 3,8 %. Thus, the use of zebu-like hybrid sires when crossbreeding with Black-andWhite cows has the positive effect on the intensity of the live weight gain of heifers, which must be taken into account in the breeding of animals in commercial farms.