Effect of Different Progesterone Protocol and Low Doses of Equine Chorionic Gonadotropin (eCG) on Oestrus Synchronization in Arabian Ewes

This experiment was conducted to determine the reproductive performance of Arabian ewes treated with short and long-term progesterone devices in addition to low doses of equine chorionic gonadotropin (eCG) during the anoestrus season. A total of 36 ewes were divided into three groups: in group I vaginal sponges (60 mg medroxy progesterone acetate; (MAP)) were applied and removed after 6 days; in group II, vaginal MAP sponges were removed 12 days following insertion, while group III served as control group. The first two groups were intramuscularly injected with of 300 IU eCG, following sponge removal. Parameters such as oestrus response rate, time to onset of oestrus, duration of oestrus, pregnancy, lambing and fecundity rates were evaluated. Blood samples were collected one day before sponge insertion and two days after sponge insertion and on day of oestrus. There were significant differences between the group I and II with control group regarding the plasma estradiol and progesterone levels. There were no significant differences in oestrus response, time to onset of oestrus, pregnancy, lambing and fecundity rates between groups I and II (P>0.05). However, differences were significant when these two treatment groups were compared with the control group. In group I, duration of oestrus was significantly higher than group II (P0.05). It was concluded that short-term sponge treatment (6 days) had better performance when compared with the long-term sponge treatment (12 days) in Arabian ewes.