Abstract
The effects of season (autumn or spring), device type (MAP sponge or CIDR device) and the number of devices (one or two) were evaluated by the superovulatory responses of ewes in a 2 × 2 × 2 factorial design. Plasma progesterone (P4) and estradio1-17β (E2) were measured to evalu-ate the characteristics of the different progestogen treatments and seasons. The embryos (1 to 8 cell stage) recovered from superovulated ewes in both seasons were cultured to examine their developmental capacity.
The mean ovulation rate of ewes treated during spring was significantly (P<0.01) lower than that of ewes treated during autumn (8.4 and 14.7, respectively), but there were no significant differences in the number of recovered ova and normal embryos between autumn and spring. Replacing the CIDR device on Day 9 of the 12-day insertion period maintained the P4 concentra-tions during gonadotropin treatment but did not improve ovulation rate, number of recovered ova and normal embryos of ewes treated in both autumn and spring. Developmental capacity of the early embryos (1 to 8 cell stage) to morulae or blastocysts did not significantly differ between autumn (45.7%) and spring (34.4%). These results indicate that the type (MAP sponge or CIDR device) and the number (one or two) of the progestogen devices did not affect ovulation rate, number of recovered ova or normal embryos, and a seasonal effect was found only in the ovula-tion rate but not in the number of recovered ova, normal embryos or the subsequent developmen-tal capacity of cultured embryos.
