Search for additional variability in the herd of Holstein cows

Abstract

Relevance. When breeding a large herd of the Holstein breed, the improvement of traits in the selection system is reflected, the integral basis (part of the basis) of which was belonging to the line. Against the background of a reduction in the number of lines, the selection of a limited number of sires related to each other into the herd, and the breeding of daughters from them by various types of rebounds, an increase in milk yield and mass fraction of protein (MPF) over three generations is reflected.Methods. The indices of the genetic value of sires in the population were evaluated according to the author's method, while taking into account the indicators of mothers and peers of the same herd. Comparison of the levels of variability of milk productivity traits in terms of standard deviations (±s) in breeding groups.Results. The relative increase in milk yield per generation for the highest lactations was 8.9–15.4% (P < 0.001), and MDL – 1.3–3.2% (P < 0.01). A comparison was made of groups of peer-daughters obtained by targeted selection of homo- and heterozygous fathers according to genetic markers of controlled EAB loci. Another aspect was the high standard deviation of milk yields in the group of daughters of homozygous fathers by 19% against the group of heterozygous, and among the crossed offspring – by 8.6% against intraline. It is assumed that this happened due to the introduction of new and rare alleles with sires into the herd.