519. INFLUENCE OF THE DURATION OF CIDR INSERTION ON OVARIAN RESPONSES IN AN ECG PROGRAM DURING NON-BREEDING SEASON IN EWES

Abstract

The aim of this study was to investigate the effect of 14 versus 7 days CIDR insertion before eCG treatment on superovulatory responses during non-breeding season in ewes. 10 Iranian Shall ewes, between 2 and 3 years old were kept inside during the experiment period and were fed a live weight maintenance ration. Ewes were randomly assigned to 1 of 2 groups. CIDR was inserted to the ewes of group 1 for 14 days and for 7 days to group 2. Each ewe received 1500 IU eCG on the day of CIDR removal. Ovarian follicular activity was monitored by transrectal ultrasonography on the days of eCG treatment, estrus, and 7 days after estrus to monitor the number of corpus lutium. During examination the animals were held in a standing position. Scanning of both ovaries was recorded using a MP4 player. The number of medium and large follicles (≥3 mm in diameter) 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 shows that the ovarian responses in terms of the number of ≥3 mm follicles at estrus is greater (P<0.05) in group 1 than group 2 ewes. The mean number of CL after eCG injection in group 1 and 2 were also significantly different (3.6±0.24 vs 2.4±0.51; P<0.05). The results showed that the 14 days synchronization before eCG treatment during non-breading seasons in ewes had the beneficial effects on ovarian responses.