BREEDING AND GENETIC ASSESSMENT OF THE HOLSTEIN DAIRY CATTLE FAMILIES OF THE STAVROPOL POPULATION

Abstract

Linebreeding is a popular and well-studied tool for breeders. However,
from a scientific point of view, the assessment of families allows improving strategy for dairy
herd development. Of particular interest are families whose foundation cows were previously
imported from other countries. In this regard, the purpose of the research was breeding and
genetic assessment of dairy cattle families. The research was carried out in one of the dairy
farms of the Stavropol Territory. In the herd of Holstein cattle, nine families were selected
and formed with consecutive numbering. They had outstanding imported foundation cows
(Hungarian selection) and at least three animals in two generations as their offspring. A
standard assessment of productive and reproductive qualities was carried out. In order to assess breeding and genetic parameters, the coefficients of correlation, regression, heritability,
selection differential (S) (by milk yield for 305 days of lactation), selection response (Δg)
were used. In order to evaluate families by the totality of generations, a modified formula for
calculating the selection index was used. The milk yield of foundation cows of the families
was at the level of 5891 – 10032 kg, as for their daughters – 6219,5 – 9137,6 kg, and as for
granddaughters – 5544 – 8010 kg. The fat content of the foundation cows of the families was
3,45 – 3,72%, their daughters – 3,53 – 3,75%, granddaughters – 3,51 – 3,80%. The variability
of this parameter for foundation cows was 164 – 444 days, for daughters – 118,5 – 283,5
days, for “granddaughters” – 99 – 233 days. In the studied families, the highest coefficient of
heritability for milk yield and service period was found in pairs of foundation cow – daughter
(0,86; 0,76) and F1-F2 (0,98; 0,96). In foundation cow – granddaughter pairs, this coefficient
was significantly lower. In the studied related groups, a positive correlation was found between milk yield and the service period, and the correlation and regression of the foundation
cows and daughters were at the same level and amounted to 0,31, 0,42 and 0,35, 0,4, respectively. For further selective breeding and formation of selection groups, we recommend the
following families: 1, 2, 3, 4, 5, 9, which have rather high rates of heritability, correlation and
selection index of families.