81 Storage of in vivo-produced embryos at refrigeration temperature before transfer to synchronised recipients in the camel (Camelus dromedarius)

In vivo embryo production through multiple ovulation and transfer is well established in camels. However, the number of embryos flushed from a donor depends on many factors, involving both the donor and the male used for breeding. Sometimes, more embryos are obtained from elite donors than the available synchronised recipients for that day. Therefore, a need arises to store these embryos until recipients synchronised for later days are available. Storing the embryos at refrigeration temperature for few days could also be helpful in the shipment of these embryos to far-off places for transfer. Keeping in view these facts, the present study was conducted to evaluate the storage of embryos flushed from the donor animals at refrigeration temperature up to 3 days before transferring them into synchronised recipients. Three elite donors used in this experiment received a combination of 2500 IU equine chorionic gonadotrophin (eCG; Folligon; Intervet), given as a single intramuscular injection on Day 1 of the treatment protocol, and 400 mg of porcine FSH (Folltropin; Bioniche) injected twice daily in declining doses of 2 × 80 mg, 2 × 60 mg, 2 × 40 mg, and 2 × 20 mg over 4 days, also beginning on Day 1. They were mated with a fertile bull on the 11th day after the start of treatment. An injection of 20 µg of gonadotrophin-releasing hormone (Receptal, Intervet) was given to them immediately after mating to induce ovulation. The embryos were collected by the nonsurgical method on the seventh day after ovulation. All embryos collected were washed in embryo-holding medium and divided into three groups. Group 1 embryos were transferred into the left uterine horn of synchronised recipients, aged 10 to 20 years, on the same day (Day 1) while group 2 and 3 embryos were stored in 500 μL of the same embryo holding medium (Ref 019449; IMV Technologies) at refrigeration (4°C) temperature after their slow cooling. They were washed in fresh holding medium before transfer to synchronised recipients on Day 2 and Day 3, respectively. Rectal ultrasound scanning was done on Day 30 and repeated on Day 90 for confirmation of pregnancy establishment. The data obtained were analysed using ANOVA. No difference (P > 0.05) was observed in the proportion of pregnancies established from stored embryos transferred on Day 2 (6/9 (66.7%) and 5/9 (55.6%)) and Day 3 (7/9 (77.8%) and 6/9 (66.7%)) compared with fresh embryos transferred on Day 1 (74.3% and 58.9%) on Day 30 and 90, respectively. In conclusion, in this study, we demonstrated that in vivo-produced embryos from elite dromedary females can be stored at refrigeration temperature in embryo holding medium for up to 3 days and can produce similar pregnancy rates as from fresh embryos transferred to synchronised recipients. This could be helpful in solving the problem of non-availability of recipients on the day of embryo flushing and the shipment of embryos to far-off places in this species. Further studies are needed to develop protocols for longer storage of embryos in this species.