COMPARATIVE ANALYSIS OF THE MORPHOLOGICAL CONDITION OF IN VIVO OBTAINS OF EMBRYOS FROM DONOR COWS OF DIFFERENT BREEDS
Authors: Koskina Iu. A. , Shekhovtsova Ya. S. , Trotskyi P. A. 
Published: July 2021

The aim of the study was a comparative analysis of the morphological status of embryos of cattle obtained in vivo from purebred and local donor cows of the I and II generations.
The object of experimental studies were obtained embryos of cattle in vivo. They were obtained in the experimental farm "Ukrainka" of the Institute of Animal Science of the UAAS of Ukraine from 1985 to 1990. Information about animals and the results of research are stored in the archives of the Private Company "Bioservice". In order to study the stages of development of seven-day-old embryos of cattle, the embryo productivity of 11 purebred and 72 local donor cows was analyzed. Purebred cows were Ayshir (4 heads), Simmental (1 head) and Ukrainian Black-and-White dairy (6 heads) breeds. Crossbreeds of the first generation were donor cows from crossing red steppe and Holstein (2 goals), Simmental and Holstein (12 goals) and Ukrainian Black-and-White dairy and Holstein (9 goals) breeds. The crossbreeds of the second generation were donor cows from crossing red steppe and Holstein (14 goals), Simmental and Montbeliard (22 goals) and Ukrainian Black-and-White dairy and Holstein (13 goals) breeds.
According to the results of the conducted research, a statistically significant difference (p < 0.01) between purebred (7.8%) and local donor cows of the I and II generation (0.6 and 1.4%, respectively) was established by the number of embryos. obtained at the stage of expanded blastocyst. There was also a statistically significant difference (p < 0.001) at the stage of late blastocyst between purebred (38.0%) and local donor cows of the I and II generation (7.1 and 9.2%, respectively). The analysis of the obtained research results shows that from purebred donor cows a significantly larger (p < 0.001) total number of blastocysts was obtained by 60.4% compared to local donor cows of the I and II generation (19.6 and 24.2%, respectively).
It was found that at the stage of late morula found significantly more embryos 44.7% and 32.9 (p < 0.01), respectively, in donor cows of the second and fourth generation compared to purebred 19.4%. It should be noted that at the stage of early morula, a significantly larger number of embryos (p < 0.001) was obtained from donor cows of the I and II generation (13.6 and 3.2%, respectively) compared to purebred 0.0%. According to the results of the comparative analysis of the total number of obtained morulae, a significantly higher number of embryos (p < 0.001) obtained from donor cows of the I and II generation (48.6 and 50.0%, respectively) was found in comparison with purebred 21.7%.
It was found that purebred donor cows received a greater 82.2% of the total number of suitable embryos compared to 68.2% (p < 0.001) of local donor cows of the first and 73.5% (p < 0.05) from local donor cows of the second generations.
Further development of extracted morulae in vitro from purebred and local donor cows on the seventh day at a temperature of 37.5°C for 15 hours led to the formation of full-fledged blastocysts at 73.0% (400 of 548).
It was found that purebred donor cows received more blastocysts (p < 0.001) compared to local donor cows of the first generation by 40.8% and 36.2% compared to local donor cows of the second generation.
It was found that from local donor cows of the second generation received 28.3%, and from local donor cows of the first generation by 26.9% more (p < 0.001) morula compared to purebred donor cows.
According to the results of the research, it was found that purebred donor cows received a higher total number of embryos (molula + blastocyst) compared to local donor cows of the first generation by 14.0% (p < 0.001) and 8.7% < 0.05) compared with local donor cows of the second generation.