Current State of In Vitro Embryo Production in African Lion (Panthera leo).

Abstract

Simple SummaryMany cat species reproduce less successfully in human care than in nature. For this reason, maintaining a viable and healthy zoo population is challenging but urgently needed as a back-up for threatened cat species in the wild. Methods of assisted reproduction have gained significance to improve reproduction in captivity. These methods include, for example, egg collection and fertilization outside the body (IVF) and the transfer of embryos back to a recipient female. For the domestic cat, IVF is well-established, and also the transfer of embryos has already resulted in healthy offspring. In this study, the IVF system developed for the domestic cat was tested on the African lion. Sperm and eggs were collected from the gonads of lions that had been euthanized for age or population management reasons. The eggs were fertilized in a laboratory with fresh or frozen–thawed sperm. Embryos were generated, demonstrating that the domestic cat IVF system is also suitable for lions. Unlike in domestic cats, the lion samples had to be transported to the laboratory from zoos distributed all over Europe. The prolonged transportation led to a loss of quality of the eggs and sperm and contributed to lower overall fertilization success.In the last 30–40 years, in vitro maturation (IVM) and fertilization (IVF) of domestic cat oocytes have been established as part of the panel of assisted reproduction technologies. As a representative of wild felids, the African lion is not yet considered endangered. Nevertheless, the zoo population management of the African lion itself as well as other closely related felids would benefit from the establishment of an IVF system. Here, we aimed to investigate the transferability of domestic cat IVF technology to the African lion. From the ovaries of 42 lionesses aged between 0.75 and 15 years, a total of 933 IVF-suitable oocytes were retrieved and subjected to IVM and IVF. The overall maturation rate was 40.6% and 18.9% of these oocytes cleaved after fertilization, respectively. Embryos were generated by intracytoplasmic sperm cell injection as well as co-culture with epididymal sperm. Improvements in the model system also led to an improved outcome with in vitro produced embryos in the lion. Compared to domestic cats, the transportation of gonads to a specialized laboratory was time-consuming and influenced oocyte quality negatively. In conclusion, the domestic cat IVF system is adoptable for the African lion, although success rates are still lower.