73 Use of embryo transfer technology to salvage the germplasm of elite dromedary camels (Camelus dromedarius) infected with brucellosis

Abstract

The present study was conducted to evaluate the potential of embryo transfer technology to salvage invivo-produced embryos from elite dromedary camels infected with brucellosis without transmission of the pathogen to the recipients or offspring. Ten elite racing champions who tested positive for brucella comprised the experimental group, whereas 3 donors negative for brucella acted as the control. Each donor animal received a combination of 2500IU of equine chorionic gonadotrophin (eCG; Folligon; Intervet), given as a single intramuscular injection on Day 1 of the treatment protocol, and 400mg of pFSH (Folltropin; Bioniche), injected twice daily in declining doses of 2×80mg, 2×60mg, 2×40mg, and 2×20mg over 4 days, also beginning on Day 1. They were mated with a fertile bull on the 11th day after the start of treatment. The donors of the group 1 received a combination of tetracycline, and streptomycin on alternate days for 2 weeks before mating with a fertile male. An injection of 20µg of gonadotrophin-releasing hormone (Receptal, Intervet) was given to them immediately after mating to induce ovulation. The embryos were collected by the non-surgical method on Day 7 day after ovulation as per the guidelines published by IETS. All embryos were washed at least 3 times in holding medium supplemented with antibiotics and then transferred individually into the left uterine horn of synchronized recipients. All recipients and calves born were tested for brucellosis every 3 weeks. The data were analysed using a two-sample t-test (Minitab statistical software, Minitab Ltd.). Results are shown in Table 1. No difference was observed in the number of embryos collected per flushing and pregnancies established at Day 60. The proportion of pregnancies reaching term from the total number of embryos transferred and from the pregnancies established on Day 60 did not differ from embryos obtained from brucella-infected and control donors. All recipients tested negative for brucellosis during their gestation and until weaning. All calves born were also negative for brucellosis on birth and until weaning and handing over to clients. In conclusion, this is the first study in camels wherein we have demonstrated that invivo-produced embryos from elite dromedary females infected with brucellosis could be collected and transferred to synchronized recipients without transmitting the pathogen to the recipients or offspring. Table 1. Pregnancies established from invivo-produced embryos collected from elite dromedary camels infected with brucellosis Donor group (N) Total number of flushings No. of embryos collected per flushing (n±s.e.m.) Pregnancies on Day 60 (% mean±s.e.m.) Pregnancies reaching term (% mean±s.e.m.) from: Embryos transferred Pregnancies on Day 60 Brucella (10) 30 5.4±0.6 55.1±2.6 44.4±2.3 83.2±3.6 Control (3) 6 5.3±0.6 65.7±6.3 53.3±6.8 80.9±7.7 P-value 0.969 0.173 0.262 0.797