A huge breakthrough for endangered rhino species in Africa has been achieved through the world’s first in-vitro fertilization (IVF) rhino pregnancy. A team has successfully implanted a lab-created rhino embryo into a surrogate rhino mother for the first time, resulting in pregnancy. This could be a big step towards saving the northern white rhino, a species on the very brink of extinction.

Producing a southern white rhino embryo via IVF is a test run for the northern white rhinos in the future. The egg came from a female southern white rhino at a zoo in Belgium and was fertilized with sperm from a male in Austria. The fetus was then implanted in a southern white rhino surrogate female in Kenya. This was the 13th attempt to achieve a viable pregnancy. 

"To achieve the first successful embryo transfer in a rhino is a huge step," Dr Susanne Holtze, a scientist at Leibniz Institute for Zoo and Wildlife Research (IZW) in Germany, which is part of the Biorescue Consortium, an international consortium trying to save this species, told BBC News.

The fates of the two of Africa's rhino species are closely intertwined. The northern white rhino (Ceratotherium simum cottoni) has just two living individuals left in the world, a mother and daughter named Najin and Fatu. Unable to reproduce, the species is essentially extinct. Scientists have been harvesting eggs from Fatu for some time, creating a stock of eggs that could one day save the species. Sperm from the last living male rhino, Sudan, has been frozen since before he died in 2018 and has been combined with Fatu's eggs to create 30 precious embryos for this very reason.

The southern white rhino (Ceratotherium simum simum) is considered much more of a success story. Previously hunted to tiny population numbers, conservation efforts have seen the population rebound to around 20,000 in the wild even though they are still heavily threatened by poaching. This is where the southern white rhinos come in to help their closely related kin. 

"I think the situation for the northern white rhino is quite privileged for the embryo transfer because we have a closely related recipient – so their internal map is nearly the same," said Professor Thomas Hildebrandt, the director of Leibniz IZW, to the BBC.

The team successfully implanted the southern white rhino embryo into a southern white rhino mother creating the world-first IVF rhino pregnancy. However such major success was followed by tragedy as the pregnant female died from an infection of Clostridia bacteria just 70 days into the pregnancy. 

A post-mortem of the mother and the fetus, which was found to be male, showed that it was 6.5 centimeters long and the team believed it had a 95 percent chance of being born alive. 

While this is a devastating blow, the success of the pregnancy proves that the technique to impregnate a rhino via IVF is possible. This is a huge step because to create a northern white rhino calf, the team will have to use a southern white rhino as a surrogate since neither of the last two living females can carry a pregnancy. 

"[W]ith this achievement, we are very confident that we will be able to create northern white rhinos in the same manner and that we will be able to save the species," said Holtze.