Five new embryos created after 10th egg collection in northern white rhinoceroses

Three years after the start of its ambitious program to save the northern white rhinoceros from extinction through advanced assisted reproduction technologies, the BioRescue consortium draws a positive interim conclusion: after the 10e When harvesting immature eggs (oocytes) in the northern white rhinoceros, female Fatu, the international team produced 5 extra embryos, bringing the total to 22, sired by two bulls. This nurtures the hope of eventually succeeding in producing new offspring and giving a keystone grazer of Central Africa a new future. At the same time, the consortium attaches the greatest importance to respecting the lives and well-being of the individual animals involved. Regular veterinary and ethical reviews of egg collection procedures show that Fatu handles the procedures well and shows no signs of adverse health effects. BioRescue is supported by the German Federal Ministry of Education and Research (BMBF).

the 10e egg collection in northern white rhinoceroses (NWR) was conducted by a team of scientists and conservationists from the Leibniz Institute for Zoo and Wildlife Research (Leibniz-IZW), Ol Pejeta Conservancy, Safari Park Dvůr Králové, Kenya Wildlife Service (KWS) & Wildlife Research and Training Institute (WRTI) on July 28, 2022, at Ol Pejeta Conservancy, Kenya. The BioRescue team was able to collect 23 eggs from Fatu, the younger of the two remaining NWR females. The egg collections of Najin, Fatu’s mother, were discontinued in 2021 after a thorough ethical risk assessment. The oocytes were immediately airlifted to the Avantea laboratory in Cremona, Italy. After maturation, 7 of the oocytes were fertilized with cryopreserved, thawed sperm from the deceased NWR male Angalifu. Finally, 5 embryos from Fatu were successfully produced and cryopreserved in liquid nitrogen.

This collection followed the 9e egg collection at the same location and by the same team on April 24the. Of the 16 oocytes collected, 3 embryos were produced in the Avantea laboratory, again using Angalifu’s sperm. The successful results of both procedures increased the total number of NWR embryos produced to 22 – all from female Fatu, half of which were fathered by the late male Suni who was born in Safari Park Dvůr Králové, Czech Republic, and the other half fathered by Angalifu who lived in San Diego Zoo Safari Park, USA.

Once the protocol for transferring the embryos to female southern white rhinoceros (SWR) recipients is optimized, the embryos will form the basis of a new NWR population, which is ultimately destined to step back in their lives. ecological role as cornerstone grazers in Central Africa.

To create suitable conditions for successful embryo transfer, the team closely monitored the interactions of the sterilized SWR bull Owuan, who acts as a oestrus detector, with the potential surrogate females who share an enclosure with him. As soon as conditions permit, the BioRescue team will attempt to perform an embryo transfer – first with SWR embryos to demonstrate that the whole procedure works well before the team uses the highly valuable NWR embryos. The team is currently considering whether adding more SWR females to the program could increase the odds of the first successful embryo transfer.

Thomas Hildebrandt, BioRescue project leader and head of the Reproduction Management Department at Leibniz-IZW: “In 2019, one day before our global first egg collection in NWR, I said: tomorrow we will change the world. Today I can say, we did that. : The 5 new NWR embryos created in one series of procedures are a new record in our mission to save the NWR from the brink of extinction. In total we succeeded in producing and cryopreserved 22 pure NWR embryos from 158 oocytes collected during 10 collections: 148 from Fatu and 10 from Nájin Our next goal is to successfully produce viable offspring by inventing and using new scientific methods and techniques for embryo transfer. What we’re doing here will lay the groundwork for future conservation rescue initiatives.”

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