VARIABILITY AND HEREDITY OF THE BULL`S BREEDING VALUE OF DIFFERENT GENEALOGICAL FORMATIONS OF THE HOLSTEIN BREED
Authors: Krugliak A. P. , Krugliak T. O. 
Published: June 2020

The results of analytical studies of breeding value variability on the basis of milk productivity, selected for reproduction of bulls of different genealogical formations of Holstein breed, are presented. A statistically significant difference between the breeding value of the milk yield of bulls and their parents of different genealogical groups was established.
The variability of bulls breeding traits and the milk productivity of their daughters in the middle of genealogical formations was dominated by similar indicators between genealogical formations.
In the middle of related genealogical formations, animals of new generations significantly outnumbered animals of earlier generations in level of breeding value.
The high correlation between breeding value of milk yield, milk fat and protein of parents and their sons was identified. The highest correlation coefficient (r = +0.643 ± 0.030) was established between the absolute milk productivity of daughters for 305 days of first lactation and the level of breeding value of milk yield of their parents, which decreased sharply when compared with their ancestors of older generations.
It was also established, that the breeding value of the animals of the new genealogical formations (sons, fathers, mothers) of Tradition 1682485 and Valiant 1650414 was always higher (on 161.2; 121.4; 209.4 kg worth), compared to the older related groups of Elevation and Chief, on which basis they have been formed. This indicates about decreasing of appearance frequency of leader bulls in a single related group during breeding.
The sons of these bulls inherit the signs of milk productivity, their breeding value exceeded that of their parents: by milk fat – by 2.4–20.0 kg, total protein – by 0.7–11.8 kg. The absolute milk production of their daughters in the 305 days of the first lactation was 11201–13173 kg of milk, 411–475 kg of milk fat and 337–383 kg of total protein, which exceeded the productivity of their contemporarys by 113–1025 kg of milk, 8.6–55.6 kg milk fat and 9.3–30.3 kg total protein.
A similar predictable of variability of the breeding value of animals of different genealogical formations of the Holstein breed for milk fat and protein in milk was established.
The level of breeding value of the fathers has the greatest influence on the level of milk production of their daughters of the Holstein breed (the influence force is 35.1%).
In second place was the force of influence breeding value of the father-fathers on the milk yield of their granddaughters, which was 11.7%. The third place was occupied by the influence of the breeding value of mothers on the level of milk productivity of their daughters (η2х = 10,6%). These forces of influence of these ancestors on the level of milk productivity of the firstborn cows are statistically significant (P < 0.05–0.001).
The last place of force of influence (η2х) on the level of milk productivity of the firstcalve heifers take the male ancestors, who are in their third line of pedigree (FFF), it was 2.7% and was not statistically significant.