One of only two remaining northern white rhinos has been retired from harvesting eggs to reproduce the next generation of the nearly extinct species.
Najin, whose eggs were being harvested for assisted reproduction, has been retired from the BioRescue conservation programme.
A consortium of science and conservation organisations involved in the groundbreaking programme announced Thursday that they would no longer harvest Najin’s eggs following an ethical risk assessment.
Besides, they said, the 32-year-old rhino's eggs were found to be unviable for the role.
Ol Pejeta head veterinarian, Dr Stephen Ngulu, said recent ultrasounds had revealed multiple small, benign tumours in Najin’s cervix and uterus as well as a large cyst in her left ovary.
Scientists started harvesting eggs from the world’s only surviving northern white rhinos, Najin and her daughter Fatu, for the conservation programme last year.
They live at the Ol Pejeta conservancy in Nanyuki where the egg harvesting has happened thrice now.
The eggs were harvested for fertilisation with sperm previously collected from male northern white rhinos. The programme is an attempt to save the species from extinction.
“In a special, in-depth ethical risk assessment, 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 (oocytes),” said the team in a press release.
This leaves the ambitious programme with just one female that can provide oocytes, Fatu.
The scientists say they do not want to further compromise Najin’s welfare through the relatively new procedure which involves hormone stimulation, full anesthesia, and trans-rectal ultrasound-guided oocyte retrieval.
Director, Wildlife Research and Training Institute (Kenya), Dr Patrick Omondi, said Najin’s advanced age and the pathological signs in her uterus led them to the decision.
“We are pleased to have participated in this assessment which affirms the collaborative and innovative approaches by the BioRescue Consortium in saving the species from extinction,” he said.
Jan Stejskal, director of international projects at Safari Park Dvůr Králové, said:
"Oocyte collections in Najin have yielded only a few (10) eggs and none of them could be fertilised successfully to become an embryo. Weighing this outcome with potential risks, the most responsible decision is to cease any further intervention on Najin and to stop using her as a donor of oocytes. She will remain a part of the programme, for example, by providing tissue samples for stem cell approaches, which can be performed with minimal invasion.”