Interestingly, the risk of anesthesia was assessed as negligible, as anesthesia was complication-free in all 65 reported procedures as well as in more than 500 procedures performed by the team in white rhinos for semen collection, health assessment or artificial insemination in the past. 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. 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. The number of oocytes collected per procedure, oocyte retrieval rate and the success rate of producing embryos considerably increased over time due to technical optimization, improved team-performance, and the accumulating beneficial effects of repeated OPUs on donor reproductive health. Of these, 75 embryos 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 team retrieved 402 oocytes, 393 of which were successfully transported to the Avantea lab, and 150 of them could be matured and fertilized by employing piezo-intracytoplasmatic sperm injection (ICSI) with a single sperm cell. Of those, 1171 follicles were punctured, flushed and aspirated. Altogether, 1505 ovarian follicles were counted via transrectal ultrasound. The set of procedures proved to be a guarantee for successful production of white rhino embryos. Silvia Colleoni and Prof Cesare Galli (from Avantea srl.) analyzed animal health and health effects of the procedures, age and seasonality, subspecies 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. Susanne Holtze (from the Leibniz-IZW), Dr. The team of authors around Prof Thomas Hildebrandt, Dr. The consortium takes animal safety and welfare, quality control and ethical risk assessment seriously and constantly evaluates its new scientific and veterinary procedures.īioRescue has performed 65 aART procedures from 2015 to 2022 and now published an evaluation of these data in the journal Reproduction. The BioRescue project, led by the Leibniz Institute for Zoo and Wildlife Research (Leibniz-IZW), 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 application of aART is the only option to create offspring for the northern white rhinoceros, a subspecies with only two individuals known to be alive-two females that cannot become pregnant anymore to carry their own embryos. These technologies enable the creation of embryos in the lab that can later be transferred into surrogate mothers to carry gestation to term. A most promising new approach is the application of advanced assisted reproduction technologies (aART) such as ovum pick-up (OPU)-the retrieval of immature egg cells (oocytes) from ovaries-and in-vitro fertilization (IVF). In fact, regular OPUs 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.Īs most rhino species and subspecies face impairment of natural reproduction and are threatened with extinction, new approaches to their conservation are required. The evaluation showed that aART is safe for the donor females with no detrimental health effects, and successful in that it yielded 51 embryos. The procedures evaluated comprised hormonal ovarian stimulation, ovum pick-up (OPU), in-vitro oocyte maturation and in-vitro fertilization (IVF), embryo culture and cryopreservation. In fact, regular OPUs benefited the reproductive health of individual female rhinos.
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