Estradiol-17 beta-oxytocin-induced cervical dilation in sheep: application to transcervical embryo transfer.
Experiments were conducted to determine whether exogenous estradiol-17beta (E2) and oxytocin (OT) can be used to improve transcervical (TC) embryo transfer (ET) procedures for sheep. Our concerns that the E2-OT treatment may alter luteal function prompted Exp. 1, in which 32 ewes were assigned to treatments in a 2x2 factorial array. On d 7 after onset of estrus, ewes received i.v. either 100 microg of E2 or diluent; 12 h later, ewes received i.v. either 400 USP units of OT or saline. To monitor luteal function, progesterone was measured in jugular blood collected from d 7 to 18. The treatments did not affect progesterone concentrations. Two trials were conducted in Exp. 2. In Trial 1, ewes were assigned to one of three treatments: TC transfer with E2-OT treatment to dilate the cervix, laparoscopic ET with E2-OT treatment, or laparoscopic ET with an equivalent diluent that did not dilate the cervix. In Trial 2, ewes were assigned to treatments in a 2x2 factorial array: TC or laparoscopic ET on d 6; E2-OT treatment for cervical dilation or diluents on d 6. Transferred embryos were recovered on d 12 in Trial 1 and d 14 in Trial 2, evaluated morphologically for development, and scored. Treatments did not affect the percentage of transferred embryos recovered. However, mode of transfer decreased (P<.01) the mean embryo development score. The E2-OT treatment increased (P<.01) the development score of embryos transferred transcervically, indicating that cervical dilation may improve the chances of embryos surviving after TC transfer. In conclusion, E2-OT treatment did not affect luteal function, and the E2-OT treatment can be used to enhance the success of TC embryo transfer in sheep.
Wulster-Radcliffe
M C
MC
Department of Animal and Poultry Sciences, Virginia Polytechnic Institute and State University, Blacksburg 24061-0306, USA.
Costine
B A
BA
Lewis
G S
GS
D000818:Animals; D002404:Catheterization / Q000662:veterinary; D002584:Cervix Uteri / Q000187:drug effects*; D004624:Embryo Transfer / Q000295:instrumentation / Q000379:methods / Q000662:veterinary*; D004958:Estradiol / Q000494:pharmacology*; D004971:Estrus; D005260:Female; D007813:Laparotomy / Q000662:veterinary; D010121:Oxytocin / Q000494:pharmacology*; D012756:Sheep
D004958:Estradiol; D010121:Oxytocin