In the vast grasslands of Ol Pejeta conservancy in Nanyuki, two majestic mammals do an almost royal walk.
They are Najin and Fatu — the world’s only surviving northern white rhinos. Both are female. They are just recovering from an egg retrieval procedure when we visit on Friday, August 23. Having been sedated for close to two hours each, they are recovering well.
The duo doesn’t know it, but on it is a load of expectations they will stop their species from extinction.
Yet, sadly, these two cannot handle a pregnancy. Najin has a pathological condition that comprises cysts and tumours preventing natural conception or handling a pregnancy to term, while Fatu — the older female and mother of Najin — has a bad hind leg that would compromise her survival if she is pregnant.
However, their ovaries are still fully functional.
This is why on Thursday, August 22, in a historic procedure, a team of veterinarians harvested eggs from the two females using assisted reproduction technology (ART) never before attempted in this species.
Using hormonal stimulation and a recently patented two-metre long ultrasound-guided device, first trialled on the southern white rhinos, the scientists were able to repeatedly and safely collect oocytes (immature eggs) through the rectum of the animals under sedation. In Najin, the scientists punctured 14 follicles and 32 in Fatu.
A professor of Bioethics from the University of Padua, Barbara de Mori, was at hand to ensure the rhinos were treated ethically during the procedure.
“We used hormone treatment to fire up activity in the ovaries of the rhinos, so that we could collect more than one oocyte. We looked inside using ultrasonography (images of internal organs) and we saw a huge number of follicles,” said A specialist in wildlife reproduction at IZW, Prof Robert Hermes.
“We harvested 10 oocytes — five from each female,” said head veterinary and capture services at Kenya Wildlife Service, Dr David Ndeereh. “They were immediately airlifted to Jomo Kenyatta International Airport to get them to Avantea — a world leader in ART for large animals in Italy, within 24 hours of collection to guarantee their viability.”
Head of veterinary services and senior reproductive management scientist at IZW, Dr Frank Goeritz said anaesthesia in rhinos is one of the most challenging procedures because it is mostly associated with decreasing the respiratory rate and, so they had to develop an endorphin-free protocol using drugs.
“We have performed about 600 procedures in search of a suitable anaesthesia protocol. But it is a lot of pressure when you realise you are working with the last two individuals of a species,” he said.
The techniques used since Thursday had been optimised following five years of experimentation on the close cousins of Najin and Fatu — southern white rhinos from 15 zoos in Europe. They successfully created hybrid embryos from the frozen northern white rhino sperm and southern white rhino oocytes in July last year.
TRANSFER INTO SURROGATES
The technique involves the direct injection of sperm into eggs. “We had four out of five of the oocytes from Fatu mature and three out of Najin’s. The matured oocytes were artificially fertilised with frozen sperm from northern white rhino bulls Suni and Sauti,” Director of Avantea, Prof Cesare Galli told HealthyNation. “We will freeze the embryos we get as we wait for establishment of the successful procedure for embryo transfer.”
According to Prof Thomas Hildebrandt of the Leibniz Institute for Zoo and Wildlife Research in Berlin, the sperms from northern white rhino bulls Suni and Sauti were frozen 13 years ago in Europe.
“We only have a small cupful of the sperm and we found the lot had a 95 per cent chance,” he said.
Even then, the scientists said they were yet to perfect the procedure required for transferring resultant northern white rhino embryos into the surrogates.
The team said it would announce from September 10 if there has been any viable embryos. But, according to director of international projects at the Zoo Dvur Kralove in the Czech Republic, Jan Stejskal, even if they were successful, the world would still have to wait at least another three years to see a northern white rhino calf born, as the average length of rhino gestation is 16 months.
The scientists said they aimed for the next egg harvest to be done in December and hopefully every four months after that.
According to Managing Director Ol Pejeta Richard Vigne, the conservancy has also started selection of southern white rhino females that could be used as surrogates. Tawan, one such female rhino, has already moved in with Fatu and Najin.