With only two living animals left, the northern white rhinoceros is almost extinct – now a team of researchers has reached an important milestone on the way to rescue. The international scientists managed to grow a rhinoceros embryo created through artificial insemination in a surrogate mother, at least for a while, as they explained on Wednesday in Berlin. Although the embryo was a comparatively common southern white rhinoceros, the method will later also be used to produce specimens of the northern subspecies.
The northern white rhinoceros is considered the rarest large mammal in the world. In total there are only two specimens left – also due to poaching: two sterile females, 23 and 33 years old, who live in Kenya. This could be the end of the subspecies; the life expectancy is between 40 and 45 years. But experts have saved sperm from male specimens and used them to fertilize eggs from the younger female. The resulting embryos will later be carried to term by a surrogate mother of the southern subspecies.
The researchers see the technology as having potential for preserving other endangered species
The embryo transfer to the surrogate mother was the first successful one in the world for pachyderms, explained participants in the BioRescue scientific program when presenting the results. The Leibniz Institute for Zoo and Wildlife Research (IZW) leads the research project. “Together we have achieved something we never thought possible,” said veterinarian and project manager Thomas Hildebrandt. We have now come a lot closer to the dream of creating a healthy and genetically stable population of northern white rhinos.
The researchers call embryo transfer a “scientific breakthrough” and see the technology as having potential for preserving other endangered species. The embryo was created in an Italian reproduction laboratory through artificial insemination and inserted into the surrogate mother in Kenya in September last year – the pregnancy was successful. However, the pregnant rhino died of an infection – and with her the 70-day-old fetus. “It was still very far from birth, so it couldn’t have been saved,” said Susanne Holtze from Leibniz-IZW. The pregnancy lasts 16 months.
The scientists are first testing their approach on the southern subspecies in order to save the valuable embryos of the northern subspecies for later experiments. In a next step, the researchers want to transfer the method to the endangered species. According to current plans, the first attempt should start in May or June of this year, said Hildebrandt. For this purpose, 30 northern white rhinoceros embryos have been created and frozen since 2019. However, it can still be years before a successful birth occurs.