One of last 2 northern white rhinos dropped from breeding project

Fatu, daughter of 32-year-old Najin, is now only donor left in programme aiming to implant artificially developed embryos into another more abundant rhino species.

Rhinos walking and grazing.
Najin (rights) and her daughter Fatu, the world's last two northern white rhinos at the Ol Pejeta Conservancy in Kenya [File: Thomas Mukoya/Reuters]

One of the world’s last two northern white rhinos is being retired from a breeding programme aimed at saving the species from extinction, scientists have said.

Najin, 32, is the mother of Fatu who is now the only donor left in the programme, which aims to implant artificially developed embryos into another more abundant species of rhino in Kenya.

There are no known living males and neither of the two remaining northern white rhinos can carry a calf to term. Scientists hope to implant embryos made from the rhinos’ egg cells and frozen sperm from deceased males into surrogate mothers.

“This decision was arrived at after an in-depth ethical risk assessment, weighing up risks and opportunities for the individuals and the entire species rendering this decision without an alternative,” the Ol Pejeta Conservancy, home to the mother and daughter, said in a statement on Thursday.

It added that oocyte collections in Najin have yielded only a few eggs to date, with none of them able to fertilise successfully into an embryo.

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.

In a statement, Biorescue cited ethical considerations for the halting of the egg harvesting and said Najin’s advanced age, as well signs of illness, were also taken into account.

“Recent ultrasound examinations had revealed multiple small, benign tumours in Najin’s cervix and uterus as well as a large cystic structure in her left ovary,” Ol Pejeta said. “These findings might explain why oocyte collections were not as successful with her as they have been with Fatu.”

In Fatu’s case, there have been so far “12 pure northern white rhino embryos”, said David Ndeereh, the acting deputy director for research at the Wildlife Research and Training Institute, a Kenyan state agency.

“We are very optimistic that the project will succeed,” he told the Reuters news agency.

The team hopes to be able to deliver its first northern white rhino calf in three years and a wider population in the next 20 years.

Source: Al Jazeera and news agencies