bringing total to 12
In another exciting step towards the future of the northern white rhino, three more pure northern white rhino embryos have been created by the international team of scientists and conservationists working to save the species. This time, they were also able to use sperm from a different bull, improving the genetic diversity of the embryos.
On July 9th, the scientists and conservationists of Leibniz Institute for Zoo and Wildlife Research (Leibniz-IZW), Safari Park Dvůr Králové, Kenya Wildlife Service and Ol Pejeta Conservancy conducted already the sixth successful oocyte collection at Ol Pejeta. Immediately, after the oocyte retrieval the 17 eggs were airlifted to Avantea laboratory in Cremona, Italy, for maturation, fertilisation, embryo development and finally cryopreservation. Two embryos could be produced using semen from northern white rhino bull Suni, who has provided the genetics for all the embryos produced up this point. This time the specialists at Avantea were also able to use semen from Angalifu, a northern white rhino bull who lived in San Diego and died in 2014. His sperm was previously thought to be incapable of successfully fertilizing eggs. However, after screening different batches of the semen utilizing pig oocytes, the scientists were able to identify a suitable batch and used it to obtain another first grade embryo. This excellent result adds the genetics of a completely unrelated individual to the cryo-preserved population, and boosts the odds for the embryo during transfer.
In a discussion prior to the ovum pick up of July 9th, the team decided not to performan oocyte collection on Najin, the older of the two remaining northern white rhinos. Her future role in the scientific programme, from an ethical perspective, will be considereddiscussed in the coming weeks from an ethical perspective and a science-backed decision will be announced. So far, none of the oocytes obtained from Nájin have been of sufficient quality for turning into viable embryos; all 12 embryos produced up to this point used oocytes from Najin’s daughter Fatu.
As retiring one individual of only two left is a serious matter from the conservation point of view, this decision will be reached in a thorough, scientific assessment among all partners and by taking into account all relevant ethical perspectives.In further developments on the ground in Ol Pejeta, the preparation of the embryo transfer enters the crucial phase. Two southern white rhino females were moved into the enclosure with Owuan, the sterilised southern white rhino bull who is serving as the oestrus detector for the females as they come into season. The team is carefully monitoring the welfare of all the animals and will start to observe and record their behaviour and also vocalizations in preparation for the first embryo transfers which are likely to begin by the end of the year.
The BioRescue research programme, significantly funded by the German Federal Ministry of Education and Research (BMBF) and additional donors such as foundation Nadace ČEZ, the philanthropist Dr Richard McLellan, Merck EMD foundation and GE HeathCare, will continue with its ambitious plan to create more embryos from oocytes collected from the northern white rhino females in a three to four-month cycle as long as the COVID-19 pandemicallows for the team to travel to Kenya. With the relocation of surrogates completed, a successful embryo transfer is the next main step the BioRescue team aims at.
Photos: Rio the Photographer