Management of recipients for an embryo transfer program in dromedary camels (Camelus dromedarius)

Embryo transfer can be used to improve the reproductive efficiency of camelids. Methods for the collection and transfer of Day 7 dromedary camel embryos are well established and the selection of good quality and well synchronised recipients has been crucial to the success of these studies. Previous results showed that the best pregnancy rates were achieved when embryos were transferred into recipients that were negatively synchronised to be one or two days behind the donor; however, as camels are induced ovulators and lack the cyclical corpus luteum (CL) of other domestic species, synchronisation of ovulation can be difficult. Consequently, methods to broaden the time window for embryos to be transferred into recipients are required. This review discusses the use of daily progesterone injections or oral treatment with meclofenamic-acid in ovulated, asynchronous recipients, as well as daily progesterone injections or treatment with a combination of progesterone and equine Chorionic Gonodotrophin (eCG) in non-ovulated recipients, to increase the number of available recipients in an embryo transfer program. Adequate pregnancy rates have been achieved in non-ovulated camels treated with progesterone and eCG (50%), ovulated, asynchronous, progesterone treated recipients (50–60%), and ovulated, asynchronous meclofenamic treated recipients (60–80%), thereby reducing the need for such tight synchrony between donors and recipients. The corpora lutea produced using these protocols can then be maintained by the ‘maternal recognition of pregnancy signal’ produced by the conceptus and thereby eliminate the need for exogenous progesterone administration throughout pregnancy.