KARYOTYPЕ VARIABILITY OF THE COWS OF UKRAINIAN RED-AND-WHITE DAIRY CATTLE BREED WITH VARIED REPRODUCTIVE ABILITY

Abstract

The results of the cytogenetic study of cows of Ukrainian red-bream dairy breeds with different reproductive ability are presented in the article. Breeding reproductive ability of cows is often and, as a rule, they include an increase in the duration of the service period, the occurrence of violations of embryonic development, stillbirth and miscarriages. Investigation of karyotype and thorough analysis of hereditary information of the herd population of herds will help to establish and eliminate the cause of reproductive failure of cows. The purpose of the study is to study the karyotype variability of cows with normal and violated reproductive qualities. The material for the research was the results of an individual assessment of the animals of the Ukrainian red-shingled breed of the DP DH "Khrystynivske" on the basis of zootechnical records and experimental cytogenetic data. To analyze the data of zootechnical accounting, the software package SUMS "Intesel Orsek" was used. Laboratory studies were conducted at the Laboratory of Biotechnology at the Institute of Animal Breeding and Genetics named after MV. Tooth The cultivation of lymphocytes, the preparation of cytogenetic drugs, the classification and recording of aberrations of chromosomes were carried out according to generally accepted techniques. The analysis of metaphase cells included cytogenetic parameters: the proportion of aneuploid and polyploid cells, the frequency of cells with structural aberrations of the chromosomes. For the cytogenetic study, based on the materials of the zootechnical account, three groups of cows have been formed, depending on their reproductive ability: I group, number 17, consists of animals with impaired reproductive ability. To II group included 33 cows, service period of which is not less than 150 days; Group ІІІ - 25 cows with a service period of 51-90 days. The study of blood lymphocytes of cows with different reproductive ability revealed a difference in the level of chromosomal instability. The results of the studies showed that in the karyotypes of animals with impaired reproductive ability, a significantly higher frequency of cells with aneuploid and polyploid chromosome sets, as well as cells with chromosomal aberrations was found to be significantly higher than that of cows with normal reproductive functions. It was established that a significantly larger proportion of cells with aneuploidy occurs in the karyotype of animals of group I, that is, in animals with a disturbed reproductive ability - 10.5 ± 2.38%. In cows of group ІІ, the frequency of cells with aneuploid number of chromosomes in blood cells decreased to 6.3 ± 1.45%. Less than twice the cows in this group and the frequency of cells with the polyploid chromosome set (from 1,0 ± 0,01 to 0,45 ± 0,16) and 15% with structural aberrations of the chromosomes (from 14,82 ± 2,87 up to 12.5 ± 2.87). In cows of group III (with normal reproductive ability), cells with aneuploid chromosomal set were found to be 2.3 times less than in cows with reproductive capacity (Group I) (P> 0.999). In the karyotypes of cows that were examined, no constitutional alterations of the chromosomes, including translocations of the Robertson type, were revealed. In animals of group I, the frequency of chromosomal aberrations was one third higher than that of animals of groups ІІ and ІІІ. The difference in frequencies between the higher and lower group values of this indicator was 4.15%. It has been established that in all groups of investigated animals there is a positive correlation between the service period and the main cytogenetic parameters. The highest positive correlation values (r = 0.70; r = 0.50; r = 0.44) are established between the duration of the service period and the frequency of structural aberrations, service period and polyploidy, service period and aneuploidy respectively in cows of the second group , In which the service period lasted 150 days or more. In cows of group I, the highest positive correlation (r = 0.48) is established between the duration of the service period and aneuploidy. For the third group, defined by us as a control, the positive relationship (r = 0.55) between the service period and aneuploidy is also established. Thus, the correlations established between the level of karyotype instability and one of the characteristics of reproductive ability (service period) indicate that the levels of karyotype instability in cows to a sufficient degree can characterize their reproductive qualities. The results of the studies show that the higher frequency of abnormal cells is found mainly in cows with broken reproductive functions. Consequently, we can conclude that for assessing the individual qualities of dairy cows, indicators of karyotype instability should be used as a criterion for evaluating the reproductive qualities of cows.