Sperm cryopreservation in rhinoceros and elephants

Cryopreservation of sperm from wild animal species has many advantages besides safeguarding genetic diversity for generations:

1. Cryopreserved sperm allows for genetic exchange between isolated or inbred populations.
2. It avoids the capture of animals from the wild for improving the genetic pool of isolated or inbred populations and long distance animal transports between countries and continents.
3. It avoids disease risks and veterinary regulations associated with live animal transport affecting wild animal transport.
4. Transport of cryopreserved sperm eases animal stress induced by transport and avoids quarantine requirements for live animal imports.

In many endangered species like rhinoceros, elephants, felids, canids, bears, primates or even bats freezing of sperm has been described, even under remote field conditions. An extreme example for the value of cryopreserving sperm and the impact it may have for the survival of an endangered species is the Northern white rhinoceros: This rhinoceros subspecies may survive only thanks to sperm cryopreserved 20 year ago.

References:

Cryopreservation in rhinoceros-Setting a new benchmark for sperm cryosurvival. Hermes R, Hildebrandt TB, Göritz F. Plos One 2018; 13: e0200154.
https://doi.org/10.1371/journal.pone.0200154

Freezing African elephant semen as a new population management tool. Hermes R, Saragusty J, Göritz F, Bartels P, Potier R, Baker B, Streich WJ, Hildebrandt TB. PLoS One 2013; 8(3):e57616.
https://doi.org/10.1371/journal.pone.0057616

Embryos and embryonic stem cells from the white rhinoceros. Hildebrandt TB, Hermes, R, Colleoni S , Diecke S, Holtze S, Renfree MB, Stejskal J, Hayashi K, Drukker M, Loi P, Göritz F, Lazzari G, Galli C. Nature Communications 2018; 9: Article Number: 2589
https://doi.org/10.1038/s41467-018-04959-2

Rewinding the Process of Mammalian Extinction. Saragusty J, Diecke S, Drukker M, Durrant B, Friedrich Ben-Nun I, Galli C, Göritz F, Hayashi K, Hermes R, Holtze S, Johnson S, Lazzari G, Loi P, Loring JF, Okita K, Renfree MB, Seet S, Voracek T, Stejskal J, Ryder OA, Hildebrandt TB. Zoo Biology 2016: 35; 280 – 292. https://doi.org/10.1002/zoo.21284

The ART of bringing extinction to a freeze – History and future of species conservation, exemplified by rhinos.

Hildebrandt TB, Hermes R, Goeritz F, Appeltant R, Colleoni S, de Mori B, Diecke S, Drukker M, Galli C, Hayashi K, Lazzari G, Loi P, Payne J, Renfree M, Seet S, Stejskal J, Swegen A, Williams SA, Zainuddin ZZ, Holtze S. Theriogenology, 18 Apr 2021, 169:76-88
https://doi.org/10.1016/j.theriogenology.2021.04.006