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Response to superovulation in exotic Merino × Polwarth ewes
THERIOGENOLOGY
S.G. Zanwar' and B.R. Deshpande2 'TechnicalOfficer, the Raymond Woollen Mills, Ltd. Jekegram lbana 400 606, India 'Read, Departmentof Animal Reproductionand Surgery Banbay VeterinaryCollege Parel, Bombay 400 012, India While pregnant mare's serum gonadotropin (PMSG) is generally used to superovulate sheep, the ovarian response is both unpredictable and highly variable among donors, which is a major problem in embryo transfer programs. In an experiment with 85 donor ewes of an exotic (Merino x Polwarth) breed, 2000 IB PMSG were injected per donor, using two different preparations(Seragon,Folligon).Intramuscularinjections of 12.5 mg progesterone were given to donor ewes for a period of 12 to 22 days to control estrus. PMSG was injected subcutaneously1 day prior to the final injection of progesterone. Donors were inseminated surgicallyon the morning of the second day after the final injectionof prcgesterone,and 4 days later embryos were recovered via laparotomy. Simultaneously, all visible ovarian structures were examined and counted. Since sufficient naturaly synchronized recipients were available, no control of estrus with progestinswas attempted. Enbryos were transferredvia laparotomy to recipientewes. Administrationof Seragon to 50 donors produced an average of 5.86 corpora lutea (CL) at various stages of development, 3.02 of them apparently not older than 1 day, and 6.76 unruptured large follicles; 3.74 ova were recovered per donor. Administration of Folligon to 35 donors resulted in an average of 3.43 CL at various stages of development, 2.06 of them apparently not older than 1 dny,and 6.0 unruptured large follicles;1.54 ova were recoveredper donor. The high incidence of delayed ovulations resulted in a high percentage of unfertilizedova (48% and 53%, respectivelyfor the Seragon and Folligon treatment groups). From the Seragon group of 50 donors, 93 embryos were transferred(an average of 1.86 embryos per donor); 53 lambs were born (57.0%). From the Folligon group of 35 donors, 25 embryos were transferred (an average of 0.71 embryos/donor); 8 lambs were born (32.0%). Based on this experience, further experiments using 1200 and 1500 IU PMXi are in progress.
JANUARY
1984 VOL. 21 NO. 1
277
S.G. Zanwar' and B.R. Deshpande2 'TechnicalOfficer, the Raymond Woollen Mills, Ltd. Jekegram lbana 400 606, India 'Read, Departmentof Animal Reproductionand Surgery Banbay VeterinaryCollege Parel, Bombay 400 012, India While pregnant mare's serum gonadotropin (PMSG) is generally used to superovulate sheep, the ovarian response is both unpredictable and highly variable among donors, which is a major problem in embryo transfer programs. In an experiment with 85 donor ewes of an exotic (Merino x Polwarth) breed, 2000 IB PMSG were injected per donor, using two different preparations(Seragon,Folligon).Intramuscularinjections of 12.5 mg progesterone were given to donor ewes for a period of 12 to 22 days to control estrus. PMSG was injected subcutaneously1 day prior to the final injection of progesterone. Donors were inseminated surgicallyon the morning of the second day after the final injectionof prcgesterone,and 4 days later embryos were recovered via laparotomy. Simultaneously, all visible ovarian structures were examined and counted. Since sufficient naturaly synchronized recipients were available, no control of estrus with progestinswas attempted. Enbryos were transferredvia laparotomy to recipientewes. Administrationof Seragon to 50 donors produced an average of 5.86 corpora lutea (CL) at various stages of development, 3.02 of them apparently not older than 1 day, and 6.76 unruptured large follicles; 3.74 ova were recovered per donor. Administration of Folligon to 35 donors resulted in an average of 3.43 CL at various stages of development, 2.06 of them apparently not older than 1 dny,and 6.0 unruptured large follicles;1.54 ova were recoveredper donor. The high incidence of delayed ovulations resulted in a high percentage of unfertilizedova (48% and 53%, respectivelyfor the Seragon and Folligon treatment groups). From the Seragon group of 50 donors, 93 embryos were transferred(an average of 1.86 embryos per donor); 53 lambs were born (57.0%). From the Folligon group of 35 donors, 25 embryos were transferred (an average of 0.71 embryos/donor); 8 lambs were born (32.0%). Based on this experience, further experiments using 1200 and 1500 IU PMXi are in progress.
JANUARY
1984 VOL. 21 NO. 1
277