Superovulation, embryo yield, quality, and embryo transfer in sheep

摘要

Two treatment regimens were used for superovulation of ewes during the reproductive season. Merino ewes and Oxford Down ewes (n = 16) were superovulated with intravaginal sponges (40 mg Norgestomet, Intervet France, 14 days) and FSH-P (Folicotropin, Spofa Prague. total dose: 10 mg). Suffolk, Tsigai and Wallachian ewes (n = 21 ) were treated with CIDR (New Zealand. 14 days) - PMSG - Ovagen. FSH-P and Ovagen were administered twice daily for 4 days since Day 12 of the treatment period. Synchronizing devices (sponges, CIDR) were removed on Day 14 in the morning. Donors were mated by the selected rain using band-service method (excluding Tsigai donors - group method). The following synchronization regimen was used in recipients: intravaginal sponges (Norgestomet 30-35 mg, Intervet France, 17 days) - 500 I.U. PMSG (Sergon, Bioveta Ivanovice in Hana) administered at time of sponge withdrawal. Synchronizing devices used in donor and recipient sets were withdrawn at the same time. Embryos were collected on Day 6 after 1st service and transferred by the laparoscopic technique (Wolf, Germany). Low and non-significant differences (P > 0.05) were found between specific sets and regimens. Data on Tsigai ewes are not included in classification of superovulation response. In total, 120 embryos were transferred to 81 recipients. 57 ewes were pregnant (70.4%). Embryos survival rate determined by the obstetric control amounted to 61.7% (74/120), i.e. 1.3 lamb per lambed recipient. The increasing number of transferred embryos (1 up to 3) was associated with an increasing number of lambs - a negative tendency was evident, however, in embryo survival rate. Data characterizing transfer of cryopreserved embryos are orientational. Pregnancy rates in recipients of vitrified embryos, fresh ones, and embryos preserved by the conventional method (in the freezer) amounted to 60.0% (3/5), 66.7% (2/3). and 22.2% (4/18), respectively (P < 0.05).