Technical report on preservation of dromedary camel embryos at 4°C for up to 72 h in catalase-supplemented media

Context Catalase, an antioxidant, prolonged camel sperm survival during storage at 5°C; however, its effect on storage of camel embryos at 4°C is unknown. Aims This study aims to evaluate the possibility of improving pregnancy rates for embryos stored at 4°C for 24–72 h in catalase-supplemented media. Methods Embryos recovered from camels flushed 8 days after mating were deposited in Eppendorf tubes containing embryo holding media, either supplemented with 500 IU catalase (Group 1) or without supplementation (Group 2). These Eppendorf tubes were placed in an Equitainer and cooled to 4°C. After 24 h, 11 embryos in each group were transferred into recipients 7 days after gonadotropin-releasing hormone injection, and the remainder was placed in the fridge at 4°C for a further 24 (n = 11/group) or 48 h (n = 11/group) before transfer. Key results A non-significant increase in pregnancy rate was achieved from embryos cooled in media containing catalase compared with the controls at 24 and 48 h, although there was no difference at 72 h (9/11 (82%) vs 5/11 (45%), 7/11 (64%) vs 2/11 (18%) and 2/11 (18%) vs 2/11 (18%), for with catalase vs controls at 24, 48 or 72 h respectively). Conclusions These results showed that there was a tendency for improved pregnancy rates at 24 (82% vs 45%) and 48 h (64% vs 18%) of cooling in catalase-supplemented media compared with controls. This improvement was not evident at 72 h. Implications The ability to keep embryos at 4°C for 24–48 h reduces the need for such tight synchronization between donors and recipients.