GENETIC FACTORS OF INFLUENCE ON THE PRODUCTIVITY OF COWS OF UKRAINIAN BLACK-AND-WHITE DAIRY BREED
Authors: Vechorka V. V. , Khmelnychyi L. M. 
Published: May 2019

The purpose of research was to study the influence of genetic factors (belonging to the line and conditional blood on the improvement breed) on the formation of milk productivity of cows in Ukrainian Black-and-White dairy breed in the basic pedigree herds (“Mayak” of Zolotonosha district of Cherkasy region and LLC “Vladana” of Sumy district in the Sumy region) in the conditions of the central and northeastern region of Ukraine at the present stage of breeding.

The level of indicators of dairy productivity of cows in the controlled herds of two breeding farms of breed which was created according to the classical scheme of reproductive crossbreeding, testified to excellent results of the breed formation. The milk yield of cows during the evaluation of seven lactations changed to third, and after the fourth, the number of animals in both households slightly decreased. For the best lactation, he equaled 6548 kg from cows of the farm "Mayak", and 7326 kg from cows of "Vladana" farm. With regard to the content of fat in milk, a very important breeding indicator – its quality, it varied within 0,78–3,86% in cows of herds of the farm "Mayak" and 3,75–3,99% – in cows herds of the economy "Vladana". However, the best possible characterization of the genetic potential of dairy animals was milk yield for the best lactation, which was determined in controlled herds of farms "Mayak" and "Vladana", respectively – 8276 and 8779 kg of milk.

According to the results of research, differentiation of indicators characterizing the milk yield of cows of Ukrainian Black-and-White milk breeds undeniably testified to the hereditary effect of genealogical formations on their variability.

In the herd of "Mayak" farm, the best were lines of Inhance 343514 and Valiant 1650414 and the genealogical line – Starbuck 352790 were found to be the best. The reliable difference of filial dgeneration of the above mentioned lines for milk yield of the first (654–1598 kg; P < 0.001) and the best (1238–2062 kg; P < 0.001) of lactation in comparison with the progeny of lines Eleveishn, Mett and P. F. A. Chif testified about their hereditary influence on the development of this trait.

Sufficiently well characterized performance indicators in the herd "Vladana" most numerous offspring of bull-sires line P. F. A. Chif with a yield for the first and best lactation respectively – 6580 and 7886 kg of milk. Their difference by this indicator at the age of the first lactation was significant in comparison with offspring of Eleveishn line (1537 kg; P < 0.001), R. Sovrin (1430 kg; P < 0.001) and Starbuck (509 kg; P < 0.001). According to the higher lactation, offspring of the sires of line P. F. A. Chif dominated on cows of remaining lines with a very high difference of 905 kg (P < 0.001; Hanover line) to 1164 kg (P < 0.001; R. Sovrein's line).

When studying the effect of conditional inheritance Holstein dairy efficiency it found that the best highest milk yield according to the first lactation were both controlled by the crossbred animal herds with a high proportion of Holstein blood, whereas in low-blooded animal milk yield was significantly less. The difference in favor of animals with Holstein heredity 87.6–100% in comparison with all groups of cows with lower blood in the herd "Mayak" was according to the first lactation from 263 kg (P < 0.01; 75.1–87.5% ) to 1765 kg (P < 0.001, 50.1–62.5%). In the herd "Vladana", high-blood animals by Holstein breed (87.6–100%) dominated on the rest group of crossbred cows for milk yield in the first lactation 704–2429 kg with high reliability (P < 0.001).

Conclusions. Created Ukrainian Black-and-White dairy breed at the present stage of breeding consolidation has been characterized by excellent results on the basis of milk productivity, regardless of the region of its use, which depending on the successful selection of genealogical formations.

Structuring of the breed into differentiated genealogical and stud lines was a prerequisite for further effective intrabreed breeding. According to the research of two leading breeding flocks found a significant impact on conventional blood by the improvement breed formation on milk production of cows, including best performance obtained by absorbing crossing.