title: Profiling patterns of fecal 20-oxopregnane concentrations during ovarian cycles in free-ranging southern white rhinoceros (Ceratotherium simum simum).
abstract: Unlike their wild counterparts, many white rhinoceros females in captivity fail to reproduce successfully such that current captive populations are not self-sustaining. The causes of the problem are poorly understood. Variation in cycle length and long periods of acyclicity are characteristics of the majority of these non-reproducing females in captivity but it is unknown whether these characteristics are a feature of reproductively successful free-ranging females. This study therefore aimed to monitor cyclic activity in a wild population of southern white rhinoceros at Lapalala Wilderness, South Africa, by measuring the concentrations of immunoreactive fecal progestagen metabolites (fPM). Five adult females were tracked twice per week for 20 months and if located a fresh fecal sample was collected. Reproductive events and group structural dynamics were also recorded and subsequently correlated with the fPM data. The baseline concentration of fPM was 0.69±0.20μg/g DW while concentrations during pregnancy were 30-400-fold higher. The females exhibited estrous cycle lengths of 30.6±7.7 days and, based on fPM data, gestation length in one female was 502±3 days. Year-round monitoring showed no clear evidence of seasonality in ovarian activity. During cyclic luteal activity females were often seen in the presence of a dominant bull. One female stopped cycling after removal of the local dominant bull and luteal activity only returned after a new bull was introduced. This suggests that white rhinoceros females in the wild might need external stimuli from a male to ovulate. These findings indicate that the irregular cyclicity reported for white rhinoceros housed in zoos and animal parks may result from conditions in captivity and account for reduced fertility.
authors.affiliation: School of Animal Biology, University of Western Australia, 1 Stirling Highway, Crawley, WA 6009, Australia; Endocrine Research Laboratory, Faculty of Veterinary Science, University of Pretoria, Private Bag X04, Onderstepoort 0110, South Africa. Electronic address: avandergoot@zoology.up.ac.za.
authors.forename: Annemieke Catharina
authors.initials: AC
authors.lastname: van der Goot
authors.affiliation: School of Animal Biology, University of Western Australia, 1 Stirling Highway, Crawley, WA 6009, Australia.
authors.forename: Graeme Bruce
authors.initials: GB
authors.lastname: Martin
authors.affiliation: Mammal Research Institute, Department of Zoology and Entomology, University of Pretoria, Hatfield, Pretoria 0028, South Africa; Centre for Integrative Physiology, University of Edinburgh, Edinburgh EH8 9XD, United Kingdom.
authors.forename: Robert Peter
authors.initials: RP
authors.lastname: Millar
authors.affiliation: Institute for Breeding Rare and Endangered African Mammals, 9 Ainslie Place, Edinburgh EH3 6AT, Scotland, UK.
authors.forename: Monique Christina Johanna
authors.initials: MC
authors.lastname: Paris
authors.affiliation: Endocrine Research Laboratory, Faculty of Veterinary Science, University of Pretoria, Private Bag X04, Onderstepoort 0110, South Africa; Mammal Research Institute, Department of Zoology and Entomology, University of Pretoria, Hatfield, Pretoria 0028, South Africa.
authors.forename: Andre
authors.initials: A
authors.lastname: Ganswindt
mesh_terms: D000818:Animals; D000835:Animals, Wild / Q000502:physiology; D030762:Estrous Cycle / Q000502:physiology*; D005243:Feces / Q000737:chemistry; D005260:Female; D010527:Perissodactyla / Q000502:physiology*; D011278:Pregnanes / Q000032:analysis*
chemical_list: C523861:20-oxo-pregnane; D011278:Pregnanes
keywords: Free-ranging; Non-invasive hormone monitoring; Ovarian cyclicity; Progestagen metabolites; White rhinoceros