[Transplantation of embryos in sheep breeding]. / Transplantatsiia na embrioni v ovtsevudstvoto.

Intra- and inter-breed transplantations were carried out with Bulgarian fresh embryos and with frozen embryos imported from Poland. A complex biotechnology was worked out, including methods of estrus synchronization, of inducing superovulation, and of producing, morphologic evaluation, storing, and transplantation of sheep embryos. Discussed are the possibilities of using embryo transplantation in sheep breeding for the fuller use of the reproductive potential of elite ewes as donors of embryos, for the introduction of new genotypes by means of importing frozen embryos as well as a modern model for fundamental investigations in the reproductive and cell biology.

[The exchange of animals in the form of embryos]. / Obmen na zhivotni pod forma na embrioni.

The results are given of transplantation work with cattle embryos from Czechoslovakia. The embryos were taken in the stage of morula or blastocyst, frozen and stored for one to ten months. Following thawing they were transplanted via surgical methods to local, estrus-synchronized recipient heifers at the Ruzhevo Konare village, Plovdiv district. A calf was born to each of six of the recipients, while two heifers that were inseminated seven days prior to transplantation yielded twins. It was considered to be the result of both the embryo-transplantation and the fertilization of own ova. Discussed are the opportunities and advantages of long-term storage and shipping of animals in the form of frozen embryos.

[Superovulation induction in buffalo cows (Bubalus bubalis) with follicle-stimulating hormone (FSH)]. / Predizvikvane na superovulatsiia pri bivolitsi (Bubalus bubalis) s folikulostimulirasht khormon (FSKh).

A total of 19 buffalo cows were used to induce superovulation following a pattern that included the use of FSH at the rate of 40 mg in the course of four days, applied twice a day and of Oestrophan at 48 hours after the beginning of treatment. Fifteen animals manifested estrus and were twice inseminated. The superovulation response of the ovaries was 4.3 +/- 0.8 yellow bodies and 0.5 +/- 0.24 follicles greater than 8 mm. A nonsurgical method was employed to obtain 24 embryos of high quality and an unfertilized ovum from 8 buffalo cows.

[Superovulation and the production of embryos in the water buffalo (Bubalus bubalis) in Bulgaria]. / Prouchvane vurkhu superovulatsiiata i poluchavaneto na embrioni pri vodniia bivol (Bubalus bubalis) v Bulgariia.

A total of thirty water buffalo cows aged 3 to 8 years were treated for superovulation over the July-October period. Nine of the animals were injected with FSH at the rate of 40 mg at 12-hour intervals in the course of 4 consecutive days, and the remaining 21 animals were injected with 3,000 IU gestyl in the middle of the luteal phase. Forty-eight hours after stimulation started both groups were treated with 500 micrograms cloprostenol. Five out of the 9 buffalo cows (55.5 per cent) of group I and 15 out of 12 buffalo cows (71.4 per cent) of group II manifested estrus at an average interval of 44.4 +/- 3.6 and 40.5 +/- 3.29 hours, respectively, following the application of cloprostenol. The superovulatory treatment of the animals of the two groups led to average values of 5.6 +/- 1.89 and 4.0 +/- 0.98 corpora lutea and 1.0 +/- 0.63 and 2.7 +/- 1.41 follicules larger than 8 mm; 2.6 +/- 1.60 and 2.1 +/- 0.94 embryos of high quality were obtained through the use of a nonsurgical method of flushing.

[Simplified method for the nonsurgical transplantation of embryos in mice]. / Oprosten metod za nekhirurgicheska transplantatsiia na embrioni pri mishki.

A new, simplified method for the nonsurgical transplantation of mouse embryos was developed. Use was made of embryos of sexually mature mice of the Balb/c and C 57BL lines, transplanted intraline or cross-like to recipients of both lines. It was established that nonsurgical methods of transplantation with laboratory animals were less time-consuming and were more readily applicable. Besides, they proved cheaper and did not require special preparatory work as they were simplified as compared with the methods known and used up to then. The new method is a valuable experimental model and contributes to the expansion of fundamental research in biology.

[Possibilities of inducing superovulation and obtaining zygotes for transplantation in sheep]. / Prouchvaniia vurkhu vuzmozhnostite za predizvikane na superovulatsiia i poluchavane na zigoti za transplantatsiia pri ovtse.

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.

[Experiments with embryo transplantation in cattle in Bulgaria]. / Opiti za transplantatsiia na embrioni pri goveda u nas.

Summarized are the results of the first attempts to transplant embryos in cattle in this country over the 1979-1982 period. An average of 6.4 ovulations have been obtained by the induction of superovulation in 48 donor heifers with the use of gonadotropic preparations (Gestyl, Anteron, Folligon) in the middle of the luteal phase at dose of 2000-2500 IU as well as with prostaglandine preparations (Estrumate, Oestrophan) injected 48 hours later. Surgical and nonsurgical methods were employed to recover a total of 78 ova (25 per cent of those that ovulated). Sixty-one (78 per cent) of them were fertilized. Forty-seven (77 per cent) of these were classified as suitable for transplantation. The surgical transplantation of 46 embryos at the age of 7 days (either morula or blastocyst) in 30 synchronized recipient heifers resulted in 9 cases of pregnancy. Three calves were live born.