[Possibilities of inducing superovulation and obtaining zygotes for transplantation in sheep]

The possibilities were explored of inducing superovulation and obtaining of zygotes from ewes of the Romanov and Tsigai breeds. The pattern used of inducing superovulation included stimulation with the serum gonadotropin preparation Gravohormone applied at the rates of 750 and 1000 IU, estrus synchronization with Estrumate (ICI, England), and ovulation with the use of the choriogonadotropin preparation Gonabion (Jenapharm, DDR). With Romanov sheep both doses of Gravohormone did not affect essentially the ovarian activity--3.4 and 3.7 ovulations were induced, whereupon a total of 5 (20%) and 10 (38%) ova were obtained from all groups of 7 animals each, 3, resp., 2 only of the zygotes being considered of high quality. With Tsigai sheep a differential ovarian response was induced--3.4 and 6.6 ovulations were produced, whereupon 5 (29%) and 15 (35%) ova were obtained, 2, resp., 7 of them being fertilized, but only 2 of the zygotes being considered fit for transplantation from the group treated with 750 IU of the preparation. No substantial differences were established in the blood plasma estradiol-17 beta and progesterone content and dynamics with the two groups of Romanov sheep treated for superovulation. Results showed that the low response of Romanov sheep, the insufficient fertilization of ova, and the low percent of zygotes capable for transplantation should be further discussed.