Originally applied on domestic and lab animals, assisted reproduction technologies (ARTs) have also found application in conservation breeding programs, where they can make the genetic management of populations more efficient, and increase the number of individuals per generation. However, their application in wildlife conservation opens up new ethical scenarios that have not yet been fully explored. This study presents a frame for the ethical analysis of the application of ART procedures in conservation based on the Ethical Matrix (EM), and discusses a specific case study-ovum pick-up (OPU) procedures performed in the current conservation efforts for the northern white rhinoceros (Ceratotherium simum cottoni)-providing a template for the assessment of ART procedures in projects involving other endangered species.

Avantea Laboratory of Reproductive Technologies Cremona Italy

Department of Comparative Biomedicine and Food Science University of Padua Legnaro Italy

Department of Reproduction Management Leibniz Institute for Zoo and Wildlife Research Berlin Germany

Department of Veterinary Medicine Freie Universität Berlin Germany

Ethics Laboratory for Veterinary Medicine Conservation and Animal Welfare University of Padua Padua Italy

Kenya Wildlife Service Nairobi Kenya

Ol Pejeta Wildlife Conservancy Nanyuki Kenya

ZOO Dvůr Králové Dvůr Králové nad Labem Czechia

Zobrazit více v PubMed

Comizzoli P, Brown JL, Holt WV. Reproductive Sciences in Animal Conservation. 2nd ed. Cham: Springer; (2019).

Comizzoli P, Holt WV. Breakthroughs and new horizons in reproductive biology of rare and endangered animal species. Biol Reprod. (2019) 101:514–25. 10.1093/biolre/ioz031 PubMed DOI

Herrick JR. Assisted reproductive technologies for endangered species conservation: developing sophisticated protocols with limited access to animals with unique reproductive mechanisms. Biol Reprod. (2019) 100:1158–70. 10.1093/biolre/ioz025 PubMed DOI

Saragusty J, Diecke S, Drukker M, Durrant B, Galli C, Göritz F, et al. . Rewinding the process of mammalian extinction. Zoo Biol. (2016) 35:280–92. 10.1002/zoo.21284 PubMed DOI

Hildebrandt TB, Hermes R, Göritz F, Appeltant R, Colleoni S, de Mori B, et al. . The ART of bringing extinction to a freeze – history and future of species conservation, exemplified by rhinos. Theriongenology. (2021) 169:76–88. 10.1016/j.theriogenology.2021.04.006 PubMed DOI

Oksanen M, Siipi H. Introduction: towards a philosophy of resurrection science. In: Oksanen M, Siipi H, editors, The Ethics of Animal Re-Creation and Modification. Reviving, Rewilding, Restoring. New York, NY: Palgrave Macmillan; (2014).

Sandler RL, Moses L, Wisely SM. An ethical analysis of cloning for genetic rescue: case study of the black-footed ferret. Biol Conserv. (2021) 257:109118. 10.1016/j.biocon.2021.109118 DOI

Emslie R. Ceratotherium simum cottoni. IUCN Red List Threat Species: e.T4183AT45 (2020). 10.2305/IUCN.UK.2012.RLTS.T4185A16980466.en PubMed DOI

Martin B. Survival of Extinction? How to Save Elephants and Rhinos. Cham: Springer; (2019).

Ellis S, Talukdar B. Dicerorhinus Sumatrensis. IUCN Red List Threat Species: e.T6553A18493355 (2020). 10.2305/IUCN.UK.2020-2.RLTS.T6553A18493355.en PubMed DOI

Ellis S, Talukdar B. Rhinoceros sondaicus. IUCN Red List Threat Species: e.T19495A18493900 (2020). 10.2305/IUCN.UK.2020-2.RLTS.T19495A18493900.en PubMed DOI

Emslie R. Ceratotherium simum spp. simum. IUCN Red List Threat Species: e.T39317AT394 (2020).

Swaisgood RR, Dickman DM, White AM. A captive population in crisis: testing hypotheses for reproductive failure in captive-born southern white rhinoceros females. Biol Conserv. (2006) 129:468–76. 10.1016/j.biocon.2005.11.015 DOI

Zegers-Hochschild F, Adamson GD, de Mouzon J, Ishihara O, Mansour R, Nygren K, et al. . International Committee for Monitoring Assisted Reproductive Technology (ICMART) and the World Health Organization (WHO) revised glossary of ART terminology, 2009. Fertil Steril. (2009) 92:1520–4. 10.1016/j.fertnstert.2009.09.009 PubMed DOI

Comizzoli P, Mermillod P, Mauget R. Reproductive biotechnologies for endangered mammalian species. Reprod Nutr Dev. (2000) 40:493–504. 10.1051/rnd:2000113 PubMed DOI

Cseh S, Solti L. Importance of assisted reproductive technologies in the conservation of wild, rare or indigenous ungulates: review article. Acta Vet Hung. (2000) 48:313–23. 10.1556/avet.48.2000.3.8 PubMed DOI

Hermes R, Göritz F, Streich WJ, Hildebrandt TB. Assisted reproduction in female rhinoceros and elephants – current status and future perspective. Reprod Domest Anim. (2007) 42:33–44. 10.1111/j.1439-0531.2007.00924.x PubMed DOI

Cocchia N, Tafuri S, Abbondante L, Meomartino L, Esposito L, Ciani F. Assisted reproductive technologies in safeguard of feline endangered species. In Wu B, editor, New Discov Embryol. (2012) 199–229. 10.5772/61004 DOI

Clulow J, Clulow S. Cryopreservation and other assisted reproductive technologies for the conservation of threatened amphibians and reptiles: bringing the ARTs up to speed. Reprod Fertil Dev. (2016) 28:1116–32. 10.1071/RD15466 PubMed DOI

Morrell JM, Mayer I. Reproduction biotechnologies in germplasm banking of livestock species: a review. Zygote. (2017) 25:545–57. 10.1017/S0967199417000442 PubMed DOI

Pennington PM, Durrant BS. Assisted reproductive technologies in captive rhinoceroses. Mamm Rev. (2019) 49:1–15. 10.1111/mam.12138 DOI

Baldassarre H, Karatzas CN. Advanced assisted reproduction technologies (ART) in goats. Anim Reprod Sci. (2004) 82–83:255–66. 10.1016/j.anireprosci.2004.04.027 PubMed DOI

Andrabi SMH, Maxwell WMC. A review on reproductive biotechnologies for conservation of endangered mammalian species. Anim Reprod Sci. (2007) 99:223–43. 10.1016/j.anireprosci.2006.07.002 PubMed DOI

Campbell MLH, Sandøe P. Welfare in horse breeding. Vet Rec. (2015) 176:436–40. 10.1136/vr.102814 PubMed DOI PMC

Kochan J, Nizański W, Moreira N, Da Silva ZC, Nowak A, Prochowska S, et al. . ARTs in wild felid conservation programmes in Poland and in the world. J Vet Res. (2019) 63:457–64. 10.2478/jvetres-2019-0043 PubMed DOI PMC

Biasetti P, de Mori B. Towards A Conservation Ethics. Iride XXXIII. (2020). p. 471−86.

Mepham B. Ethical analysis of food biotechnologies: an evaluative framework. In: Mepham B, editor Food Ethics. London; New York, NY: Routledge; (1996).

England GCW, Millar KM. The ethics and role of AI with Fresh and Frozen semen in dogs. Reprod Domest Anim. (2008) 43:165–71. 10.1111/j.1439-0531.2008.01157.x PubMed DOI

Millar K. Ethics and ethical analysis in veterinary science: the development and application of the ethical matrix method. In: Wathes C, Corr S, May S, McCulloch S, Whiting M, editors, Veterinary and Animal Ethics. Oxford: Wiley-Blackwell; (2013).

Gamborg C. The acceptability of forest management practices: an analysis of ethical accounting and the ethical matrix. For Policy Econ. (2002) 4:175–86. 10.1016/S1389-9341(02)00007-2 DOI

Millar K, Tomkins S. Ethical analysis of the use of GM fish: emerging issues for aquaculture development. J Agric Environ Ethics. (2007) 20:437–53. 10.1007/s10806-007-9051-z DOI

Bremer S, Millar K, Wright N, Kaiser M. Responsible techno-innovation in aquaculture: employing ethical engagement to explore attitudes to GM salmon in Northern Europe. Aquaculture. (2015) 437:370–81. 10.1016/j.aquaculture.2014.12.031 DOI

De Mori B, Ferrante L, Florio D, Macchi E, Pollastri I, Normado S. A protocol for the ethical assessment of wild animal-visitor interactions (AVIP) evaluating animal welfare, education, and conservation outcomes. Animals. (2019) 9:487. 10.3390/ani9080487 PubMed DOI PMC

Biasetti P, Florio D, Gili C, de Mori B. The ethical assessment of touch pools in aquariums by means of the ethical matrix. J Agric Environ Ethics. (2020) 33:337–53. 10.1007/s10806-020-09823-2 DOI

Howard BJ, Beresford NA, Nisbet A, Cox G, Oughton DH, Hunt J, et al. . The strategy project: decision tools to aid sustainable restoration and long-term management of contaminated agricultural ecosystems. J Environ Radioact. (2005) 83:275–95. 10.1016/j.jenvrad.2005.01.013 PubMed DOI

Cotton M. Evaluating the “ethical matrix” as a radioactive waste management deliberative decision-support tool. Environ Values. (2009) 18:153–76. 10.3197/096327109X438044 DOI

Biasetti P, Ferrante L, Bonelli M, Manenti R, Scaccini D, de Mori B. Value-conflicts in the conservation of a native species: a case study based on the endangered white-clawed crayfish in Europe. Rend Lincei Sci Fis Nat. (2021) 32:389–406. 10.1007/s12210-021-00987-1 DOI

Beauchamp TL, Degrazia D. Principles and principlism. In: Khushf G, editor. Handbook of Bioethics. Dordrecht: Springer; (2004).

Beauchamp TL. Standing on Principles. Oxford: Oxford University Press; (2010).

Biasetti P, de Mori B. The ethical matrix as a tool for decision-making process in conservation. Front Environ Sci. (2021) 9:e584636. 10.3389/fenvs.2021.584636 DOI

Emslie R, Brooks M. African Rhino. Status Survey and Conservation Action Plan. IUCN/SSC African Rhino Specialist Group. Gland; Cambridge: IUCN; (1999).

Hermes R, Hildebrandt TB, Walzer C, Göritz F, Gray C, Niemuller C, et al. . Estrus induction in white rhinoceros (Ceratotherium simum). Theriogenology. (2012) 78:1217–23. 10.1016/j.theriogenology.2012.05.015 PubMed DOI

Hildebrandt TB, Hermes R, Colleoni S, Diecke S, Holtze S, Renfree MB, et al. . Embryos and embryonic stem cells from the white rhinoceros. Nat Commun. (2018) 9:2589. 10.1038/s41467-018-04959-2 PubMed DOI PMC

Sandler R. The ethics of reviving long extinct species. Conserv Biol. (2014) 28:354–60. 10.1111/cobi.12198 PubMed DOI

Campbell DI, Whittle PM. Resurrecting Extinct Species. Ethics and Authenticity. New York, NY: Palgrave Macmillan; (2017).

Groves CP, Fernando P, Robovský J. The sixth rhino: A taxonomic re-assessment of the critically endangered northern white rhinoceros. PLoS ONE. (2010) 5:e9703. 10.1371/journal.pone.0009703 PubMed DOI PMC

Hermes R, Göritz F, Portas TJ, Bryant BR, Kelly JM, Maclellan LJ, et al. . Ovarian superstimulation, transrectal ultrasound-guided oocyte recovery, and IVF in rhinoceros. Theriogenology. (2009) 72:959–68. 10.1016/j.theriogenology.2009.06.014 PubMed DOI

Hildebrandt TB, Holtze S, Biasetti P, Colleoni S, de Mori B, Diecke S, et al. . Conservation research in times of COVID-19 – the rescue of the Northern White Rhino. J Appl Anim Ethics Res. (2021) 3:1–22. 10.1163/25889567-BJA10009 DOI

Biorescue Ethical Team . The role of Najin in the Biorescue project: An ethical assessment. (2021). Available online at: https://www.izw-berlin.de/files/biorescue/FINAL_Report_Najin_October_2021.pdf

Foose TJ, Wiese RJ. Population management of rhinoceros in captivity. Int Zoo Yearb. (2006) 40:174–96. 10.1111/j.1748-1090.2006.00174.x DOI

Owen-Smih RN. Megaherbivores. The Influence of Very Large Body Size on Ecology. Cambridge: Cambridge University Press; (1988).

Waldram MS, Bond WJ, Stock WD. Ecological engineering by a mega-grazer: White Rhino impacts on a south African savanna. Ecosystems. (2008) 11:101–12. 10.1007/s10021-007-9109-9 DOI

Cromsigt JPGM, te Beest M. Restoration of a megaherbivore: landscape-level impacts of white rhinoceros in Kruger National Park, South Africa. J Ecol. (2014) 102:566–75. 10.1111/1365-2745.12218 DOI

Ceballos G, Ehrlich PR, Raven PH. Vertebrates on the brink as indicators of biological annihilation and the sixth mass extinction. Proc Natl Acad Sci USA. (2020) 117:13596–602. 10.1073/pnas.1922686117 PubMed DOI PMC

Saragusty J. Genome banking for vertebrates wildlife conservation. In: Katkov I, editor,Current Frontiers in Cryobiology. IntechOpen (2012). 10.5772/1962 DOI

Ryder OA, Friese C, Saragusty J, Greely HT, Sandler R, Durrant BS, et al. . Exploring the limits of saving a subspecies: the ethics and social dynamics of restoring northern white rhinos (Ceratotherium simum cottoni). Conserv Sci Pract. (2020) 1–8. 10.1111/csp2.241 DOI

Céline A, Luque GM, Courchamp F. The twenty most charismatic species. PLoS ONE. (2018) 13:e0199149. 10.1371/journal.pone.0199149 PubMed DOI PMC

Foose TJ. Global management of rhinos. In: Ryder OA, editor. Rhinoceros Biology and Conservation. San Diego, CA: San Diego Zoological Society; (1993).

Branton M, Richardson JS. Assessing the value of the umbrella-species concept for conservation planning with meta-analysis. Conserv Biol. (2010) 25:9–20. 10.1111/j.1523-1739.2010.01606.x PubMed DOI

Fraser D. Understanding Animal Welfare. Oxford: Wiley-Blackwell; (2008).

Lambert RDC, Bernard JE, Rioux R, Béland D, Montreuil DA. Endoscopy in cattle by the paralumbar route: technique for ovarian examination and follicular aspiration. Theriogenology. (1983) 20:149–61. 10.1016/0093-691X(83)90210-8 DOI

Pieterse MC, Kappen KA, Kruip TAM, Taverne MAM. Aspiration of bovine oocytes during transvaginal ultrasound scanning of the ovaries. Theriogenology. (1988) 30:751–62. 10.1016/0093-691X(88)90310-X PubMed DOI

Pieterse MC, Vos PLAM, Kruip TAM, Wurth YA, van Beneden TH, Willemse AH, et al. . Transvaginal ultrasound guided follicular aspiration of bovine oocytes. Theriogenology. (1991) 35:857–62. 10.1016/0093-691x(91)90426-e PubMed DOI

Menchaca A, Barrera N, dos Santos Neto PC, Cuadro F, Crispo M. Advances and limitations of in vitro embryo production in sheep and goats. Anim Reprod. (2016) 13:273–8. 10.21451/1984-3143-AR871 DOI

Galli C, Crotti G, Notari C, Turini P, Duchi R, Lazzari G. Embryo production by ovum pick up from live donors. Theriogenology. (2001) 55:1341–57. 10.1016/S0093-691X(01)00486-1 PubMed DOI

Galli C, Duchi R, Colleoni S, Lagutina I, Lazzari G. Ovum pick-up, intracytoplasmic sperm injection and somatic cell nuclear transfer in cattle, buffalo and horses: from the research laboratory to clinical practice. Theriogenology. (2014) 81:138–51. 10.1016/j.theriogenology.2013.09.008 PubMed DOI

Carter JA, Bellow S, Meintjes M, Perez O, Ferguson E, Godke RA. Transvaginal ultrasound-guided oocyte aspiration for production of embryos in vitro. Arch Anim Breed. (2002) 45:99–108. 10.5194/aab-45-99-2002 DOI

Meintjes M, Bellow MS, Broussard JR, Paccamonti D, Eilts BE, Godke RA. Repeated transvaginal ultrasound-guided oocyte retrieval from pregnant mares. Theriogenology. (1994) 41:255. 10.1016/S0093-691X(05)80165-7 DOI

Brogliatti GM, Palasz AT, Adams GP. Ultrasound-Guided transvaginal follicle aspiration and oocyte collection in llamas (Lama glama). Theriogenology. (1996) 45:249. 10.1016/0093-691X(96)84722-4 PubMed DOI

Boni R, Roviello S, Zicarelli L. Repeated ovum pick-up in italian mediterranean buffalo cows. Theriogenology. (1996) 46:899–909. 10.1016/S0093-691X(96)00248-8 PubMed DOI

Boni R. Ovum pick-up in cattle – a 25-yr retrospective analysis. Anim Reprod. (2012) 9:362–9. Available online at: https://www.animal-reproduction.org/article/5b5a605af7783717068b46f3/pdf/animreprod-9-3-362.pdf

Galli C, Duchi R, Crotti G, Lazzari G. Embrio production by ovum pick up in water buffalo. Theriogenology. (1998) 49:400. 10.1016/s0093-691x(98)90753-1 PubMed DOI

Jacobson CC, Choi YH, Hayden SS, Hinrichs K. Recovery of mare oocytes on a fixed biweekly schedule, and resulting blastocyst formation after intracytoplasmic sperm injection. Theriogenology. (2010) 73:1116–26. 10.1016/j.theriogenology.2010.01.013 PubMed DOI

Broadbent PJ, Dolman DF, Watt RG, Smith AK, Franklin MF. Effect of frequency of follicle aspiration on oocyte yeld and subsequent superovulatory response in cattle. Theriogenology. (1997) 47:1027–40. 10.1016/S0093-691X(97)00060-5 PubMed DOI

Mari G, Merlo B, Iacono E, Belluzzi S. Fertility in the mare after repeated transvaginal ultrasound-guided aspirations. Anim Reprod Sci. (2005) 88:299–308. 10.1016/j.anireprosci.2005.01.002 PubMed DOI

Lazzari G, Colleoni S, Crotti G, Turini P, Fiorini G, Barandalla M, et al. . Laboratory production of equine embryos. J Equine Vet Sci. (2020) 89:103097. 10.1016/j.jevs.2020.103097 PubMed DOI

Chastant-Maillard S, Quinton H, Lauffenburger J, Cordonnier-Lefort N, Richard C, Marchal J, et al. . Consequences of transvaginal follicular puncture on well-being in cows. Reproduction. (2003) 125:555–63. 10.1530/rep.0.1250555 PubMed DOI

Albero G, Longobardi V, Zullo G, De Carl E, Martucciello A, Salzano A, et al. . 144 influence of repeated ovum pickup on buffalo welfare. Reprod Fertil Dev. (2014) 26:185. 10.1071/RDv26n1Ab144 DOI

McEvoy TG, Alink FM, Moreira VC, Watt RG, Powell KA. Embryo technologies and animal health - consequences for the animal following ovum pick-up, in vitro embryo production and somatic cell nuclear transfer. Theriogenology. (2006) 65:926–42. 10.1016/j.theriogenology.2005.09.008 PubMed DOI

Petyim S, Båge R, Madej A, Larsson B. ovum pick-up in dairy heifers: does it affect animal well-being? Reprod Domest Anim. (2007) 42:623–32. 10.1111/j.1439-0531.2006.00833.x PubMed DOI

Vanderwall DK, Woods GL. Severe internal hemorrhage resulting from transvaginal ultrasound-guided follicle aspiration in a mare. J Equine Vet Sci. (2002) 22:84–6. 10.1016/S0737-0806(02)70094-4 DOI

Velez IC, Arnold C, Jacobson CC, Norris JD, Choi YH, Edwards JF, et al. . Effects of repeated transvaginal aspiration of immature follicles on mare health and ovarian status. Equine Vet J. (2012) 44:78–83. 10.1111/j.2042-3306.2012.00606.x PubMed DOI

Cuervo-Arango J, Claes AN, Stout TA. A retrospective comparison of the efficiency of different assisted reproductive techniques in the horse, emphasizing the impact of maternal age. Theriogenology. (2019) 132:36–44. 10.1016/j.theriogenology.2019.04.010 PubMed DOI

Hildebrandt TB, Schnorrenberg A, Weißmann I. German Patent No 10 2017. 002 614. Vorrichtung zur Entnahme von Oozyten bei lebenden Tieren, insbesondere bei großen Säugetieren (2018).

Portas TJ. A review of drugs and techniques used for sedation and anaesthesia in captive rhinoceros species. Aust Vet J. (2004) 82:542–9. 10.1111/j.1751-0813.2004.tb11196.x PubMed DOI

Mora IM, Langan JN, Ryan S, Aitken-palmer C, Michael J. Repeated anesthesia in a black rhinoceros (Diceros Bicornis) to manage upper respiratory obstruction. J Zoo Wildl Med. (2018) 49:1041–6. 10.1638/2018-0095.1 PubMed DOI

Atkinson MW, Hull B, Gandolf R, Blumer E. Repeated chemical immobilization of a captive greater one-horned rhinoceros (Rhinoceros unicornis), using combinations of etorphine, detomidine, and ketamine. J Zoo Wildl Med. (2002) 33:157–62. 10.1638/1042-7260(2002)033[0157:RCIOAC]2.0.CO;2 PubMed DOI

Heard DJ, Olsen JH, Stover J. Cardiopulmonary changes associated with chemical immobilization and recumbency in a white rhinoceros (Ceratotherium simum). J Zoo Wildl Med. (1992) 23:197–200. Available online at: http://www.jstor.org/stable/20095208

Kock MD, Morkel P, Atkinson M, Foggin C. Chemical immobilization of free-ranging white rhinoceros (ceratotherium simum simum) in hwange and matobo national parks, zimbabwe, using combinations of etorphine (m99), fentanyl, xylazine, and detomidine. J Zoo Wildl Med. (1995) 26:207–19. Available online at: http://www.jstor.org/stable/20095464

Bush M, Raath JP, Grobler D, Klein L. Severe xypoxaemia in field-anaesthetised white rhinoceros (Ceratotherium simum) and effects of using tracheal insufflation of oxygen. J South African Vet Assoc. (2004) 75:79–84. 10.4102/jsava.v75i2.457 PubMed DOI

Radcliffe RW, Morkel P. Rhinoceroses. In: West G, Heard D, Caulkett N, editors. Zoo Animal and Wildlife Immobilization and Anesthesia. Ames: Wiley; (2014).

Brink CF, Erasmus J. Etorphine poisoning. S Afr Med J. (2003) 93:761–2. 10.7196/SAMJ.2349 PubMed DOI

Haymerle A, Fahlman Å, Walzer C. Human exposures to immobilising agents: Results of an online survey. Vet Rec. (2010) 167:327–32. 10.1136/vr.c4191 PubMed DOI

Hermes R, Hildebrandt TB, Walzer C, Göritz F, Patton ML, Silinski S, et al. . The effect of long non-reproductive periods on the genital health in captive female white rhinoceroses (Ceratotherium simum simum, Cs cottoni). Theriogenology. (2006) 65:1492–515. 10.1016/j.theriogenology.2005.09.002 PubMed DOI

Owen-Smith RN. The social system of the white rhinoceros in 1. In: Geist V, Walther F, editors. The Behaviour of Ungulates and Its Relation to Management. Morges: IUCN; (1974). p. 341–51.

Hermes R, Hildebrandt TB, Göritz F. Reproductive problems directly attributable to long-term captivity-asymmetric reproductive aging. Anim Reprod Sci. (2004) 82–83:49–60. 10.1016/j.anireprosci.2004.05.015 PubMed DOI

Hermes R, Göritz F, Saragusty J, Stoops MA, Hildebrandt TB. Reproductive tract tumours: the scourge of woman reproduction ails Indian Rhinoceroses. PLoS ONE. (2014) 9:e0092595. 10.1371/journal.pone.0092595 PubMed DOI PMC

Chan KMA, Balvanera P, Benessaiah K, Chapman M, Díaz S, Gómez-Baggethun E, et al. . Why protect nature? Rethinking values and the environment. Proc Natl Acad Sci USA. (2016) 113:1462–5. 10.1073/pnas.1525002113 PubMed DOI PMC

Biasetti P, de Mori B. A framework of values: reasons for conserving biodiversity and natural environments. Etica Polit. (2016) 18:527–45. Available online at: https://www.openstarts.units.it/bitstream/10077/13529/1/BIASETTI_DE-MORI_EP_2016_3.pdf

Harrington LA, Moehrenschlager A, Gelling M, Atkinson RPD, Hughes J, Macdonald DW. Conflicting and complementary ethics of animal welfare considerations in reintroductions. Conserv Biol. (2013) 27:486–500. 10.1111/cobi.12021 PubMed DOI

Cinková I., Shrader A.M. Individuality, species-specific features, and female discrimination of male southern white rhinoceros courtship calls. Anim Cogn. (2022). 10.1007/s10071-021-01591-4. [Epub ahead of print]. PubMed DOI

Göritz F, Hermes R, Walzer C, Zainuddin ZZ, Payne J, Hildebrandt TB. Etorphine free anesthesia protocols optimized for frequent reproductive interventions ranging from semen collection, artificial insemination to ovum-pick-up (OPU) in four rhino specis. In: Sci Progr 15th Int Elephant Rhino Conserv Res Symp Singapore, November 14-18. Singapore: (2016). p. 50–51.

Morkel P, Nel P. Updates in African Rhinoceros field immobilization and translocation. In: Fowler ME, Miller RE, editors. Fowler's Zoo and Wild Animal Medicine Current Therapy, Vol. 9. Elsevier (2019). p. 692–8. 10.1016/b978-0-323-55228-8.00098-9 DOI

Radcliffe RW, Ferrell ST, Childs SE. Butorphanol and azaperone as a safe alternative for repeated chemical restraint in captive white rhinoceros (Ceratotherium simum). J Zoo Wildl Med. (2000) 31:196–200. 10.1638/1042-7260(2000)031[0196:BAAAAS]2.0.CO PubMed DOI

De Mori B, Spiriti MM, Pollastri I, Normando S, Biasetti P, Florio D, et al. . An ethical assessment tool (ETHAS) to evaluate the application of assisted reproductive technologies in mammals' conservation: the case of the northern white rhinoceros (Ceratotherium simum cottoni). Animals. (2021) 11:312. 10.3390/ani11020312 PubMed DOI PMC