One of the world’s last two northern white rhinos, a mother and her daughter, is being retired from a breeding program aimed at saving the species from extinction, scientists said on October 19.
Najin, 32, is the mother of Fatu. She is now the only donor left in the program, which aims to implant artificially developed embryos into another more abundant rhino species in Kenya.
There are no known living males, and neither of the two remaining northern white rhinos can carry a calf to term.
Northern white rhinos, which are actually grey, used to roam freely in several countries in east and central Africa, but their numbers fell sharply due to widespread poaching for their horns.
A Biorescue team led by researchers from the Leibniz Institute for Zoo and Wildlife Research in Germany has been racing against time to save the world’s most endangered mammal.
“The team has reached the decision to retire the older of the two remaining females, 32-year-old Najin, as a donor of egg cells,” Biorescue said in a statement, citing ethical considerations.
Najin’s advanced age, and signs of illness, were also taken into account, they said.
Scientists hope to implant embryos made from the rhinos’ egg cells and frozen sperm from deceased males into surrogate mothers.
“We have been very successful with Fatu… So far, we have 12 pure northern white rhino embryos,” David Ndeereh, the acting deputy director for research at the Wildlife Research and Training Institute, a Kenyan state agency, told Reuters.
“We are very optimistic that the project will succeed.”
The team hopes to be able to deliver its first northern white rhino calf in three years and a broader population in the next two decades.
Najin is one of the last two northern white rhinos left in the world, BBC states.
The last male of this species died in 2018, but his semen was collected and fertilized eggs.
During this procedure, a group of veterinarians removes a rhinoceros egg using methods developed over years of research.
The eggs are then sent to an Italian laboratory, where they are fertilized with the sperm of two dead males.
So far, scientists have created 12 embryos that they hope to implant in surrogate mothers selected from a population of southern white rhinos.
A whole species of rhino can disappear in the world
“Retiring one individual from a conservation program because of animal welfare considerations is usually not a question to think about for long… but when one individual is 50% of your population, you consider this decision several times,” said head veterinarians Frank Göritz and Stephen Ngulu.
As well as her advanced age, ultrasound scans had revealed several small, benign tumors on Najin’s cervix and uterus and a cyst on her left ovary.
But BioRescue said she would remain part of the scheme in other ways, like providing tissue samples for stem cell research.
It’s hoped she can also “transfer her social knowledge and behavior” to future offspring.
Northern white rhinos have been brought to the brink of extinction by poaching and loss of habitat.
Najin was born in a Czech zoo but was moved a decade later to Ol Pejeta Conservancy in Kenya, where she lived under armed protection.
