CIDR estrous synchronization in the Arabian Oryx (Oryx leucoryx)

In Jordan, the Arabian Oryx (Oryx leucoryx) is considered among the most important wild ungulates. The Arabian Oryx is listed as vulnerable species according to the International Union for Conservation of Nature (IUCN). Based on author's knowledge, estrus synchronization in the Arabian Oryx has never been investigated. Therefore, the current study aimed to validate a Controlled Internal Drug Release (CIDR) estrus synchronization technique for the first time in 7 Arabian Oryx females. Prior to CIDR application, animals were subjected to transabdominal ultrasonic examination twice, two weeks apart to exclude pregnancies. A single CIDR was inserted (Day 0) for a period of 7 days. At the time of CIDR removal (Day 7), animals were administered a single injection of prostaglandin F2α (PF2α) and equine chorionic gonadotropin (eCG). Blood samples were collected from all animals before, during and after CIDR removal for progesterone (P₄) analysis. Animals were monitored for estrus behavior for 8 days starting 24 h after CIDR removal. All animals were considered to be anestrous at the start of the study as defined by having blood progesterone <1 ng/ml prior to insertion of the CIDR. All animals displayed estrous behavior between Day 1-3 after CIDR removal and the average interval from CIDR removal to estrus and length of estrus were 53.71 ± 5.59 h and 55.43 ± 6.19 h, respectively. On Day 14 (6 days after CIDR removal) P4 concentrations rose above 1 ng/ml indicated ovulation. It is possible to synchronize estrus in Arabian Oryx using CIDRs. The success of CIDR estrous synchronization in female Arabian Oryx, as described in the current study, opens new perspectives towards the possible application of assisted reproductive techniques for the propagation and conservation englishEnglishof this vulnerable species.