The use of biotechnological reproduction methods is a relevant issue since the embryo transfer, obtained after stimulating superovulation, can accelerate reproduction and improve the number of cattle. The purpose of the study was to evaluate the effectiveness of various schemes for stimulating superovulation in cows of the Ukrainian black-pock dairy breed. Therewith, the study analysed the ovarian response to the drug “FSH-Super” under different introduction schemes: Step-up (gradual increase in the dose) and Step-down (gradual dose reduction) and recorded the number of embryos suitable for transplantation. Donor cows were administered the drug “Estrofan” to synchronise the sexual cycle. After 7 days, the drug “Ovarelin” was injected, and after another 7 days, the injection of the drug “Estrofan” was repeated in the same dose. Stimulation of superovulation began on the 10th day of the sexual cycle with the drug “FSH-super” in the form of eight gradually increasing (Step-up) and gradually decreasing (Step-down) doses within 4 days. Artificial insemination was performed 12 and 24 hours after the start of oestrus. During the study, it was discovered that in the group of cows with gradual dose reduction of the drug “FSH-Super”, 83.3% reacted with superovulation, and in the group with the gradual increase – only 71.4%. Therewith, the number of yellow bodies on two ovaries in a donor cow averages 15.6 and 9.2, respectively. An average of 12.4 and 7.8 embryos (Step-down and Step-up) were obtained from the donor, of which 7.8 and 4.2 are suitable for transplantation, respectively. However, in the group of cows with gradually decreasing doses, a higher number of embryos unsuitable for transplantation was obtained – 4.6 and unfertilised oocytes – 2.6, compared with the group of donors with gradually increasing doses, where these indicators are 3.6 and 1.0, respectively. Thus, the use of the drug “FSH-super” to donor cows according to the step-down introduction scheme allows getting more embryos suitable for transplantation. This will allow managing the biotechnological aspects of cattle reproduction and effectively and in a controlled manner accelerate the breeding process in farms of various forms of ownership, fixing the desired genotype in the herd

Intracytoplasmic spermatozoid injection (ICSI) is one of the commonest methods used in assisted reproductive technologies in human medicine. However, this procedure has low efficacy for bovines, mainly because of insufficient activation of oocytes after spermatozoid microinjection. One of the most effective methods of activating oocytes is considered to be the use of phosphorus calcium, though the optimal concentration of activator and its effect on pre-implant development of embyo are still open questions. An oocyte-cumulus complex of clinically healthy cows, retrieved from the ovaries during slaughter, matured over 22–24 h in in vitro conditions. Oocytes with visible polar body had been subjected to intracytoplasmic spermatozoid injection (ICSI), and were 15–30 min later activated in the environment with different concentrations of calcium ionophore for 15–20 min and then transferred for further cultivation in a culture medium with sodium pyruvate. The fertilization rate was identified on the second day at the 2–4th stages of cellular embryo, and the quality of obtained embyos was evaluated on day 8. Based on the statistical analysis of the data, we determined that the artificial activation of bovine oocytes using calcium ionphore after intracytoplasmic spermatozoid injection (ICSI) led to statistically significant improvement in conception and ratio of blastocytes obtained to oocytes injected. In the study, we confirmed that addition of 5, 10 and 50 µМ of the agent had the same efficacy on the activation of occytes of bovine cattle. However, it has to be noted that during further cultivation of the obtained zygotes up to the blastocyte stage (day 8), we saw no significant differences in quality of embryos obtained. Therefore, use of calcium ionophore for the activation of bovine oocytes after intracytoplasmic spermatozoid injection is effective, for it promotes increase in fertilization parameters and ratio of blastocytes obtained to oocytes injected, facilitating production of higher numbers of embyos suitable for transplantation or cooling. Our previous conclusions are valuable for increasing the efficacy of methods of intracytoplasmic injection of bovine spermatozoid and its further use for purposes of science and production.

Producing embryos in vitro is an important technology used to improve the genetic potential of cattle and perfect the programs of their breeding. Regardless of the way they are produced, all embryos that had not been used for transplantation to recipients must be conserved. Because of significantly increased interest in the problem of cryoconservation of embryos, both coming from scientists and businesses, there are emerging new commercial environments that allow the facilitation of cryoconservation and the increase in the embryo survival. Oocyte-cumulus complexes obtained from the ovaries of slaughtered clinically healthy cows matured in 22–24 h in in vitro conditions. The oocytes were co-cultured with spermatozoids in Fertilization medium, and the obtained zygotes were cultured in Culture medium with Sodium-Pyruvate for 4 or 7 days up to the stage of morula or blastocyste, respectively. For the vitrification of cow embryos, we used a commercial kit for the vitrification of human embryos, having compared the duration of equilibration. According to the results of the studies, we observed high efficiency of cryoconservation of cow embryos using the commercial kit for vitrification of human embryos. The results revealed the significant effect of equilibration on survival and further development of embryos. In addition, we described the dependence of development stage of cattle embryo on the duration of the contact of embryo with equilibration solution. Therefore, optimal time of contact of cattle embryos at the morula stage with equilibration solution was 12 minutes. On the 24th h after thawing, 46.7 ± 3.3% of the embryos were observed to undergo blastulation, and on 48th h, this parameter increased to 96.7 ± 3.3%, which corresponded to the parameters in the group of embryos that had not been subjected to cryoconservation. In the conditions of further cultivation, the percentage of blastocystes that hatched in the experimental group was no different from that of the control. At the same time, the highest efficiency of vitrification of blastocystes of cows was seen after the contact with the equilibration solution for 15 min, since the percentage of hatched blastocystes was the same as in the control group. Therefore, using the commercial kit for vitrification of human embryos is beneficial, for it promotes the parameters of cow embryos after vitrification/thawing that are similar to such of intact embryos (without freezing). The data we analyzed and presented in the paper could help to increase the efficiency of cryoconservation of cattle embryos for both scientific and commercial purposes.

Toxoplasma gondii is the agent of toxoplasmosis, which is common to both humans and cattle. That is why the goal of work was to study the spreading of the agent of toxoplasmosis among cattle in certain regions of Ukraine, which in turn will make it possible to predict the appearance of the disease among people and prevent the development of its clinical signs. Whole blood or serum samples of cattle of different ages and sexes from farms in Kyiv, Zhytomyr, Khmelnytskyi and Lviv regions of Ukraine were sent to the laboratory for research. The presence of total antibodies to T. gondii was determined in the serum of the animals. To do this, we used the method of enzyme-linked immunosorbent assay using test kits from different manufacturers in accordance with the guidelines. In general, the prevalence of T. gondii among cattle in Kyiv, Zhytomyr, Khmelnytskyi and Lviv regions of Ukraine according to the results of studies was 10.3% (95% confidence interval: 6.7-15.1). At the same time, the study of animals was carried out in two stages, in 2014 and 2018, and the prevalence did not differ significantly. Thus, in 2014, according to the results of research, a positive reaction to the agent of toxoplasmosis was detected in 10 samples or 13.9% (95% confidence interval: 7.3- 23.4), while in 2018 this figure was 11 samples or 8.4% (95% confidence interval: 4.5-14.1) of the studied animals. Also, in 2014 and 2018 studies found that the highest level of seroprevalence of the agent of toxoplasmosis in both years of research was registered in cattle from farms of Zhytomyr and Kyiv regions was 11.9% (95% confidence interval: 4.5-24.4) and 11% (95% confidence interval: 5.9-18.3), respectively. During the conducted research, an increase in the prevalence of T. gondii with the age of animals was statistically significant. Among animals under six months of age, of the 65 serum samples tested, 3 tested positively to the agent (4.6; 95% confidence interval: 1.2-12.1), while in the group of animals older than three years (49 cows) 10 samples were positively responded (20.4; 95% confidence interval: 10.9- 33.4) compared to the previous group of animals, the P-value was 0.0114. So, the data obtained indicate the presence of the agent of toxoplasmosis among cattle in Ukraine, which requires further study and development of approaches to prevent human infection when eating meat and dairy products of positively reacting animals