It was found that milk productivity of testable cows from the Shchors pedigree plant was higher on 983 kg of milk (Р>0,95), on 20 kg of milk fat (Р<0,95), and on 11 kg (Р<0,95) of milk albumen as compared to the productivity of cows of pedigree plant  "Agrosvit". Content of fat and albumen in milk the best results had cows from pedigree plant “Agrosvit” on 0,19 and 0,13 (Р>0,999) respectively.

With the help of cytogenetic monitoring of dairy cattle in the herds from the Shchors pedigree plants and  "Agrosvit" it was determined that karyotype  of greater part of the investigated cows corresponds to the norm, however one third of these cows had mutative cells and variable chromosomes in karyotype.

It was also found that in the investigated cows of herds from the Shchors pedigree plant the total percentage of mutative cells is 17,0% and in cows of herds from “Agrosvit” this data is twice higher – 35.8% (Р>0,999).

The index of aneuploidy in the cows of herds from the Shchors pedigree plant was 12,5 % and from “Agrosvit” was 15.6% higher (Р>0,999) and made up 28,1 %. The percentage of polyploidy in the investigated cows of herds from the Shchors pedigree plant made up 0,8%, in “Agrosvit” polyploidy cells were not founded.

The part of metaphase with the asynchronous breaking up of center areas of chromosomes for the tested cows of the Ukrainian Black-pied dairy breed made up in the Shchors pedigree plant 1,3% and in "Agrosvit" 2,4 % at unreliable difference between indexes (Р < 0,95). This index can be used as a marker on dairy cattle breeding because it characterizes intracellular processes in the organism of animals, stipulated by the features of metabolism, peculiar to the display of capacity for the certain type of productive realization.

A percent of chromosomal aberrations in the tested cows of herd from the Shchors pedigree plant is 2,4 % and in "Agrosvit" is 5,3 % Р>0,999). Research of cytogenetic changeability of the bought cows (n = 6) of herd from the  pedigree plant  "Agrosvit" gave the next results: total amount of mutative cells in the bought animals occured with frequency 37,1 % that on 0,9 % more  (Р<0,95) than for the animals of own reproduction and a portion of mutative cells was 36,2% .

Including great amount of aneuploidy cells on 0,5 % (Р <0,95) and almost twice as high index of chromosomal aberrations 7,8 % versus 4,7 % (Р <0,95) was discovered in karyotype of the bought animals, as compared to analogical indices for the animals of own reproduction. However, frequency of cells with asynchronous cleaving of centromeric regions of chromosomes (ACCRH)  in karyotype of animals of own reproduction is 3,41% that exceeds this index on 2,71 % in bought animals, that is 0,7 % (Р >0,95).

In the tested cows from the Shchors pedigree plant not high, positive but reliable cross-correlation connection between the general part of mutative cells and yield of cows’ milk 0,108 (Р <0,95) was determined. In the tested cows "Agrosvit" was also determined positive, but unreliable cross-correlation connection between the general amount of mutative cells and yield of  cows’ milk 0,229 (Р <0,95), between anueplody and yield of milk 0,184 (Р <0,95). And also between the yield of milk and chromosomal aberrations 0,131 (Р <0,95) and between the yield of milk and ACCRCH 0,247 (Р <0,95). Low connection was determined between the amount of mutative cells and milk productivity (r = 0,108-0,299, P <0,95). It proves that cytogenetic indices reflect chromosomal status of animals and is the certain marker of intensity of metabolism in the organism of animals that result in the increase of yields of milk of cows.

The estimation of karyotypical changeability of dam population will allow in a short time to educe and withdraw carriers of high level of chromosomal violations.

Key words: the Ukrainian Black-pied dairy cattle, milk productivity, cytogenetic monitoring, karyotype, chromosomes, mutative cells.