Growth and development of calves of different genetic background in the pre-weaning period

Abstract

Development of a living organism, including periods of its development, follows certain laws. All mammals have a pre-weaning period. In calves, the pre-weaning period lasts 6 months. This period is known to be one of the most important, since at this time the body, firstly, adapts to new environmental conditions, and secondly, starts to live on typical feeds. The calf growth depends on many factors, including genetic ones. The study of the dynamics of live weight in calves in the pre-weaning period with regard to their genetic background is of practical relevance. The farm uses bulls of both Holstein black-motley cattle of domestic selection and Holstein breed of foreign selection. A general pattern in monthly live weight increase has been found for descendants of all the bulls. At the same time, the growth rate in groups of calves sired by different bulls differed by months of rearing. In calves sired by the bull Mers, the absolute weight gain by months of rearing ranged from 10.0 kg (4 months) to 36.0 kg (6 months), that is, the growth failure in the previous period was compensated for by increased growth rate in the next month. At the same time, calves sired by the bulls Gavano, Cassio and Bentley showed a uniform absolute weight gain by months of rearing. In general, calves sired by the bulls Cassio and Gavano grew better. They were superior to other calves in the absolute weight gain over the entire period, which attained 138.5 and 132.2 kg, and it was higher by 6.3–20.9 and 5.3–14.6 kg or 4.5–15.1% and 4.0–11.0%, respectively.