516. THE EFFECTS OF ECG INJECTION ON SUPEROVULATORY RESPONSES BEFORE VERSUS AFTER CIDR REMOVAL IN IRANIAN SHALL EWES

Abstract

The aim of this study was to investigate the effects of eCG injection on ovarian responses 2 days before or immediately after CIDR removal in a superovulation program during non-breeding season in Iranian Shall ewes. 12 ewes were kept inside for the duration of the experiment and were fed a live weight maintenance ration. The ewes were synchronized by CIDR. The day of CIDR insertion was considered as the starting point of the experiment (day 0). The ewes received 1500 IU eCG on day 12. Ewes were randomly assigned to 1 of 2 groups, and CIDR removed on days 12 and 14 in groups 1 and 2, respectively. Ovarian follicular activity was monitored by transrectal ultrasonography daily from the initiation day of superovulatory stimulation (day 12) until the day of estrus (day 14), and once 7 days after estrus (day 21) to monitor the number of corpus lutium. During examination the animals were held in a standing position. Ultrasonographic scanning of both ovaries was recorded using a MP4 player. The number of medium and large follicles (≥3 mm) were recognized, measured and mapped to their location using printed images of both ovaries. Data were analyzed using GLM procedure of the SAS. The results presented in Table 1 showed that the ovarian responses in terms of the number of ≥3 mm follicles at estrus and CL 7 days later were greater (P<0.05) in group 1 ewes. The results indicated that the superior time for eCG injection is on the day of CIDR removal.