Influence of homozygosis by marker alleles of blood groups on the productivity, reproductive qualities and longevity of cows

Abstract

Currently, in populations of different cattle breeds there is elimination of a number of alleles of blood groups and an in-crease in the homozygosity coefficient that leads to rise in the amount of homozygous animals. In this regard, the aim of the research was to study the effect of homozygosity by EAV-locus of blood groups on the productive and reproductive characteristics of cows. The research was carried out on the farms of the Smolensk region for breeding of Sychevskaya cattle breed: the “Rybkovskoye” breeding farm and pedigree breeding unit Agricultural Production Cooperative (APC) named after Uritsky. On these farms there were selected 2078 cows, homozygous according to alleles of EAV - locus of blood groups and heterozygous animals born in 2010-2014 (21 and 581, 50 and 1426 heads, respectively). The study has shown that the average milk yield over the productive life of homozygotes in the herd of the “Rybkovskoye” farm is insignificantly lower and on the farm named after Uritsky this parameter is significantly higher. Application of one-way ANOVA analysis determined the weak effect of genotype on the productivity of animals on the “Rybkovskoe” farm only for the first lactation with factorial effect in milk yield, milk fat and protein 1.2, 1.5 and 1.1%, respectively. On the breeding farm named after Uritsky the factorial effect in milk yield and fatyield for the second lactation was 0.3 and 0.4%, and on the average over the life in milk yield it was 0.4%. The analysis of repro-ductive qualities: the age of the first calving, the age of the first fruitful insemination, multiplicity of insemination to lactation, the number of days before the first insemination in the current lactation, the duration of open days revealed close values, similar nature of distribution and variation of these indicators, absence of statistically significant differences between them in homozy-gotes and heterozygotes. A weak (2% or less) influence of homozygosity on productive longevity, which determines the superiority of homozygous cows over heterozygous, characteristic for samples from both farms, has been found.