Assisted reproductive technologies in captive rhinoceroses

Survival of the five remaining rhinoceros species is threatened. Four of the five species are in managed collections, but captive populations are not self-sustaining and low reproductive rates make population growth slow. Slow population growth, coupled with behavioural incompatibilities, acyclicity, low genetic diversity, and disease susceptibility, creates the need for assisted reproductive technologies (ARTs) to maintain genetic diversity while bolstering population numbers. Both published and unpublished data are included in this review of ARTs, to facilitate understanding consistencies and variations between and within each rhinoceros species. Progress has been made to address species-specific characteristics of reproductive physiology in rhinoceroses. This review outlines the ARTs that have been performed and identifies areas in need of research. In vivo technologies have resulted in live calves by artificial insemination, created genetic reservoirs through semen collection, and provided new avenues of gamete retrieval via ovum pickup. In vitro technologies have enabled genetic rescue post mortem and support early stage embryo production through oocyte maturation and fertilisation. As conservation efforts focus on rhinoceroses, improvement of existing techniques and development of new technologies will allow for a broader application of successful rhinoceros ARTs.