The dissertation is devoted to the study of the chromosomal polymorphism of somatic cells of certain species of farm animals of the Bovidae family, the development of cytogenetic parameters of various indicators of productivity and reproductive function, and further effective use in the breeding process.
By means of comparative cytogenetic analysis the participation of individual chromosomes in aberrations was investigated, the dependence of individual cytogenetic characteristics of chromosomal variability on pedigree and species affiliation was determined, intercellular and individual polymorphism of the number of active NOR chromosomes was established, and the positive correlation with the significance of milk chromosomes with significance of chromosomal sets in species of animals belonging to different genera and evolutionary changes in karyotype were analyzed.
7259 metaphase chromosome preparations from 259 animals were examined by microscopy. Preparation of drugs, analysis of morphology, classification and accounting of chromosome aberrations were performed according to conventional methods.
From the analyzed 916 metaphase plates, of 35 sheep of Roman breed the share of aberrant cells is 15,22%. Cytogenetic analysis of 792 metaphase plates of 33 Sokil sheep showed that the proportion of aberrant cells was 20,92%. The analysis of 722 metaphase plates of 25 sheep of Ukrainian Carpathian-mountain breed found that the proportion of aberrant cells was 19,22%. Features of chromosomal variability of sheep depending on their productive qualities are established.
In the course of the study, specific chromosomal rearrangements and associations of two acrocentric chromosomes were identified in individual animals of the Roman breed. The difference in individual indicators of chromosomal variability in sheep was determined depending on their reproductive capacity. The NOR activity is higher in the animals that bring 3 or more lambs.
The chromosomal variability of cattle gray Ukrainian and Ukrainian red-mottled dairy breeds was investigated. In the karyotypes of individual cows, translocations of the Rt 1/29 and cells with monosomy by sex chromosomes were detected. In a cow with an inventory number 6040 in SE “Khristinovske” a set of chromosomes 2n=59 was found. Using G-banding, the presence of a Rt 13/23 pairs was determined.
Associations of signs of chromosomal instability and reproductive capacity in cows of Ukrainian red-mottled dairy breed were established. Based on the analysis, it was concluded that the most stable karyotype have cows with average productivity.
Results of analysis of the polymorphism of Ag-stained chromosomes indicate an increase in the number of NORs in the chromosome sets of cows with increasing milk yield per lactation. A direct correlation between milk yield and cell frequency with a polyploid set of chromosomes (r=0,94) was established.
Based on cytogenetic studies, a method for selecting animals according to the cytogenetic profile with the best reproductive and productive features has been developed.
Analysis of the chromosomal variability revealed the lowest rate of chromosomal instability of river buffaloes (14,35%) comparing to other animal species. In different sex groups of buffaloes, the frequency of chromosomal mutations was almost at the same level, accounting for 13,60% in females and 13,39% in males. In individual animals, such structural changes in chromosomes as “S-shaped” and ring chromosomes were detected. In the chromosomal set one buffalo revealed a partial monosomy due to the terminal deletion of a 2-pair chromosome. In an adult female revealed a 2-pair chromosome duplication and a 3-pair chromosome rupture. In the karyotype of individual female buffaloes, the coexistence of two genetically different cell populations derived from one zygote was recorded, as well as the presence of cells with monosomy due to the absence of one of the sex chromosomes. Polymorphism of Ag-stained chromosomes of buffaloes is represented by a limit of active NORs from 1 to 12 with an average number of 2,82%.
The results of the analysis of chromosome sets using the G-banding method of our species of animals of the family Bovidae, indicate a similar striation of their differentially colored chromosomes. Thus, among the known conserved areas from the marked association of chromosomes between 1/3, 2/8, 5/11 in sheep and 1/25, 2/23, 8/19, 5/28, 16/29 in river buffaloes and, apparently, the distribution of these areas occurred during the formation of these species. The emergence of new associations is marked by the genomes of species of a particular taxon, and it is these chromosomes that are most often involved in aberrations.
The results suggest that chromosomal variability indicators can serve as an effective criterion for productive and reproductive features of farm animals and allow early detection of individuals with undesirable genetic changes at an early age.
