EMBRYO FLUSHING IN COWS UNDER VARIOUS SUPEROVULATION SCHEMES

Abstract

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