Embryo transfer in the dromedary camel (Camelus dromedarius) using non-ovulated and ovulated, asynchronous progesterone-treated recipients

The aim of the present study was to investigate the use of exogenous progesterone and equine chorionic gonadotrophin (eCG) in non-ovulated and ovulated, asynchronous dromedary camel recipients being prepared for an embryo transfer programme. The uteri of 12 mated donor camels were flushed non-surgically 7 days after ovulation and 42 embryos were recovered. In Experiment 1, 16 embryos were transferred non-surgically to recipients on Day 3 or 4 after ovulation (ov+3 and ov+4, respectively). Each recipient received a daily dose of 75 mg, i.m., progesterone-in-oil from 2 days before embryo transfer until 6 days after ovulation. Thereafter, the progesterone dose was reduced to 50 mg on Day 7 and finally to 25 mg day(-1) on Days 8 and 9. Nine of 16 recipients (56%; ov+3, n=4; ov+4, n=5) became pregnant compared with none of eight non-progesterone treated controls, into which embryos were transferred on Day 4 after ovulation. In Experiment 2, 18 non-ovulated recipients received 75 mg, i.m., progesterone-in-oil daily from 3 days before until 12 days after non-surgical transfer of a Day 7 blastocyst, at which time pregnancy was diagnosed by ultrasonography. All pregnant recipients continued to receive 75 mg progesterone-in-oil daily for a further 6 days, when each camel received 2000 IU, i.m., eCG. Progesterone treatment was then reduced to 50 mg day(-1) and, when a follicle(s) ≥1.3 cm in diameter were present in the ovaries, each animal received 20 μg buserelin to induce ovulation. Once the corpora lutea had developed, progesterone treatment was reduced to 25 mg day(-1) for a final 3 days. Fourteen of 18 recipients (78%) became pregnant and seven of these (50%) remained pregnant after eCG treatment. Of the seven pregnancies that were lost, two were lost before eCG treatment, two did not respond to eCG treatment and three responded to eCG treatment and ovulated, but lost their pregnancies 6-8 days after the last progesterone injection.