74 Body condition of donor animal and recipients affects the outcome of embryo transfer program in dromedary camel (Camelus dromedarius)

Abstract

The present study was conducted in dromedary camels to evaluate the effect of the body condition of donor animals on the outcome of superstimulation and embryo collection in experiment 1 and the establishment of pregnancies in the recipients in experiment 2. The animals were physically evaluated for their body condition and scored on a scale of 0 to 5 (0 being very thin and weak, while 5 being very fat). They were divided into three groups based on their body condition score (BCS). Animals with a score of 1–2, >2–3, and >3–4 were divided into groups 1, 2, and 3, respectively. Animals with a score of <1 and >4 were considered either too weak or too fat and were not included in the study. In Experiment 1, 32 donors in 3 groups were superstimulated with 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. The ovaries of all the donor camels were scanned on Day 4 after the start of treatment, and thereafter at intervals of one or two days until the majority of follicles had grown to between 1.3 and 1.8 cm in diameter before mating with a fertile male. Each donor received an intramuscular injection of 20 µg of gonadotrophin-releasing hormone (Receptal, Intervet) immediately after mating, and embryos were collected by non-surgical method on Day 7 after ovulation. In Experiment 2, 141 recipients divided in 3 groups, as described above, were synchronized with donors and received an embryo each in their left uterine horn. The pregnancy confirmation was done by an ultrasound examination on Day 50 after transfer. Data were analysed by ANOVA with Fisher protected least significant difference test (Minitab statistical software, Minitab Ltd.). In experiment 1, the mean ± s.e.m. number of follicles (13.9 ± 1.3; 12.7 ± 2.9; 15.0 ± 1.7), and the percent mean ± s.e.m. of embryos collected (41.5 ± 7.7; 57.0 ± 12.3; 60.4 ± 7.8) were not different among groups 1, 2 and 3, respectively. However, the percent mean ± s.e.m. of transferrable embryos obtained were higher (P < 0.05) in group 3 (77.7 ± 4.8) compared with group 1 (57.5 ± 10.1). Similarly, in experiment 2, the percent mean ± s.e.m. of pregnancies achieved in group 3 (68.9 ± 6.4) was similar to that of group 2 (57.9 ± 14) but higher (P < 0.05) than that of group 1 (50.5 ± 10.0). In conclusion, to the best of our knowledge, this is the first study showing a direct correlation between the BCS and outcome of embryo transfer program in camels. Donors with a good BCS produced more transferrable embryos, and conception rates were higher in recipients having a better BCS. This clearly shows that not only is the selection of recipients critical in the embryo transfer program, but donors with a positive energy balance yield better transferrable embryos. Priming of donors before the start of the breeding season could help to improve the outcome of this technology in camels.