76 Effect of season on the superstimulation response, embryo quality, and pregnancy establishment in dromedary camel (Camelus dromedarius)

Abstract

The present study was conducted to study the effect of season on the superstimulation response, embryo quality and pregnancy establishment in the dromedary camels. Two donors each were superstimulated in the month of June 2019 (non-breeding season) and January 2019 (breeding season) by a combination of 2500 IU of equine chorionic gonadotrophin (eCG, Folligon; Intervet), given as a single intramuscular injection on Day 1 of the treatment protocol, and 400 mg of pFSH (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 scanned by rectal ultrasonography and follicles counted before mating with a fertile bull on Day 11 after the start of treatment. An injection of 20 µg of gonadotrophhin-releasing hormone (Receptal, Intervet) was given immediately after mating to induce ovulation. The number of corpora lutea (CL) were counted, and the embryos collected by the non-surgical method on Day 7 after ovulation. All embryos were washed and graded before they were transferred individually into the left uterine horn of recipient animals, synchronized to be on Day 6 after ovulation. All recipients were screened by ultrasonography on Day 22, Day 60, and Day 90 for pregnancies. The data were analysed using a two-sample t-test (Minitab statistical software, Minitab Ltd.). No difference was observed in the mean number of follicles developed (20.5 vs. 18.5) between the donors in breeding and non-breeding season, respectively. The percent mean ± s.e.m. of ovulations as observed by counting the CL in nonbreeding season (80.7 ± 3.4) were not different from those in breeding season (85.4 ± 3.7). A total number of 16 embryos collected during non-breeding season and 20 embryos in breeding season were transferred to recipients. The percent mean ± s.e.m. of pregnancies established on Day 22 (56.6 ± 3.4 vs. 67.5 ± 7.5) and on Day 90 (47.2 ± 2.8 vs. 60 ± 0.0) were similar in both groups. These observations indicate that embryo transfer technology can be applied to camels during the summer months, which is considered the non-breeding season, and pregnancies can be established at par with breeding season. In conclusion, to the best of our knowledge, this is the first study in camels wherein we have demonstrated that donor camels can be superstimulated, embryos can be collected, recipient animals can be synchronized, and pregnancies can be established in the summer (non-breeding) months. The embryos collected from elite donors can be transferred to synchronized recipients to establish pregnancies or preserved for future use. Some owners do not want calves to be born in summer months, so protocols need to be established for storing these embryos for a few months before their transfer to recipients, to have the calves delivered in the desired winter months.