A new analysis by scientists has shown that advanced technologies seeking to prevent the extinction of the northern white rhino are safe.
In a new scientific analysis published in the journal “Reproduction”, experts found out that state-of-the-art technology has no detrimental health effects.
Scientists evaluated 65 assisted reproduction technology (aART) procedures that comprised hormonal ovarian stimulation, ovum pick-up, in-vitro oocyte maturation and in-vitro fertilisation, embryo culture, and cryopreservation conducted from 2015 to 2022.
“In fact, regular ovum pick-ups benefited the reproductive health of individual female rhinos by improving ovarian function, increasing follicle numbers, and instigating the regression of pathological structures such as ovarian cysts,” the study says.
The study says most rhino species and subspecies face impairment of natural reproduction and are threatened with extinction.
As such, new approaches to prevent them from going extinct are required.
The study says the application of the technology is the most promising approach.
“These technologies enable the creation of embryos in the lab that can later be transferred into surrogate mothers to carry gestation to term.”
The study says the application of advanced assisted reproduction technologies (aART) is the only option to create offspring for the northern white rhinoceros.
The subspecies has only two individuals known to be alive—two females that cannot become pregnant anymore to carry out their own embryos.
Led by the Leibniz Institute for Zoo and Wildlife Research (Leibniz-IZW), it develops and pioneers these technologies to enhance the breeding success of southern white rhinos in human care and to save the northern white rhino from extinction.
The new technology is being applied at Ol Pejeta Conservancy to try and prevent the northern white rhino from going extinct.
The two remaining female rhinos, Najin and Fatu, who live in Ol Pejeta, are unable to carry a pregnancy.
The consortium takes animal safety and welfare, quality control, and ethical risk assessment seriously and constantly evaluates its new scientific and veterinary procedures.
The team of authors around Prof Thomas Hildebrandt, Dr Frank Göritz, Dr Susanne Holtze (from the Leibniz-IZW), Dr Silvia Colleoni, and Prof Cesare Galli (Avantea) analySed animal health and health effects of the procedures, age and seasonality, subspecses and origins of individuals, hormonal status and cyclicity, as well as the effects of the stimulation protocol in relation to OPU and IVF success rates with 20 southern and two northern white rhino females.
They found out that the set of procedures proved to be a guarantee for the successful production of white rhino embryos.
Altogether, 1505 ovarian follicles were counted via transrectal ultrasound.
Of those, 1171 follicles were punctured, flushed, and aspirated.
The team retrieved 402 oocytes, 393 of which were successfully transported to the Avantea lab.
150 of them could be matured and fertilised by employing piezo-intracytoplasmatic sperm injection (ICSI) with a single sperm cell.
75 embryos were cleaved, and 51 blastocysts were finally cryopreserved: 19 southern, 22 northern, and 10 hybrids with southern white rhino oocytes and northern white rhino sperm.
The number of oocytes collected per procedure, the oocyte retrieval rate, and the success rate of producing embryos considerably increased over time owing to technical optimization, improved team performance, and the accumulating beneficial effects of repeated OPUs on donor reproductive health.
The scientists said the repeated OPUs yielded no indications of adverse effects on general and reproductive health, such as inflammation, pathological alterations, or a declining response to ovarian stimulation.
“There was no evidence for detrimental effects of repeated OPU procedures with prior hormonal stimulation on reproductive health, fertility, cycling activity, ovarian morphology, follicle numbers, or success across all levels of the IVF program.”