The current investigation aimed to establish a fixed-time induction of ovulation/ insemination protocol in camels superovulated by different equine chorionic gonadotropin (eCG) regimens during the transition period in Egypt (mid-October to mid-November). Seventeen pluriparous camels, Camelus dromedarius, were used. All females retained controlled intra-vaginal drug releasers (CIDRs) for 13 consecutive days, and at CIDR withdrawal, the camels were randomly divided into three groups. The control group (n = 5) received 1 ml saline intra-muscularly (i.m.), whereas remaining camels were superovulated by 2500 IU eCG either in a single shot (SS, n = 6) or in serial decreasing doses over 3 days (DD, n = 6). Ovarian dynamics were monitored by transrectal ultrasonography at 2-day intervals, and ovulation was induced by 5000 IU hCG i.m. The changes in reproductive hormones throughout the period of the study were determined. The results showed that mean values of total no. of follicles and size of dominant follicles remained low (P < 0.05) in all groups until day of CIDR removal. Thereafter, total follicle no. increased (P < 0.05) in both superovulated groups compared to the control, where the dominant follicles attained the highest (P < 0.05) diameter 12 days after the eCG treatment. Double-ovulation rate was higher (P < 0.05) in SS (50%) and DD (66.6%) groups compared to that of control (0.0%). However, 33.3% of the SS group developed large anovulatory follicles (ø > 25 mm), which did not respond to induction to ovulation. These results elucidate that eCG administration in serial decreasing doses generates a reliable superovulatory response in camels, and ovulation can be blindly induced 12 days after the gonadotropin treatment. This fixed-time hormonal protocol represents a sufficient alternative to conventional day-to-day ultrasonography and would have profound implication for enhanced fertility in dromedary camels by facilitating infield application of embryo transfer technique.
Keywords: Dromedary camels; Estradiol 17-β; Ovulation rate; Superovulation; eCG.