APPLICATION OF MODERN BIOTECHNOLOGICAL AND GENETIC METHODS IN THE SYSTEM OF PRESERVING THE GENE POOL OF THE UKRAINIAN BROWN DAIRY BREED.

The authors investigated the possibility of using modern biotechnological methods for obtaining in vitro embryos from females of the local breed with the desired complex genotype by the A2A2/BB beta- and kappa-casein, cryopreservation and long-term storage in the system of preserving the gene pool. During the first stage of work, 27 oocytes-cumulus complexes (OCCs) were obtained from the ovaries of heifers, of which 66.7% were selected as suitable for in vitro cultivation, and from the ovaries of cows - 69.2% of oocytes-cumulus complexes (45 of the 65 obtained oocytes-cumulus complexes) were suitable for further cultivation. Our cytogenetic analysis of heifer egg cells showed that 33.3% (9 out of 27 cultured oocytes-cumulus complexes) of cells were at the metaphase II stage of meiosis, and 66.7% had chromosomal disorders. The second stage involved the fertilization of egg cells matured outside the body. During this stage, it was found that the level of zygote formation on average reached 23.8%, and further cultivation also provided in vitro fragmentation of embryos at the level of 22.2% (10 embryos from 63 inseminated eggs). It was found that the overall level of embryo formation after fertilization of egg cells of cows matured outside the body was 33.3%. For the conservation and rational use of breeding (genetic) resources of cattle at the cellular level, it is necessary to create cryobanks of gametes for long-term storage in order to further sell them for reproduction. [ABSTRACT FROM AUTHOR]