Validation of fecal glucocorticoid metabolite assays for south African herbivores

Sathya K. Chinnadurai, Joshua J. Millspaugh, Wayne S. Matthews, Kirsten Canter, Rob Slotow, Brian E. Washburn, Rami J. Woods

Research output: Contribution to journalArticlepeer-review

22 Scopus citations


Fecal glucocorticoid metabolite (FGM) assays are a popular means of monitoring adrenocortical activity (i.e., physiological stress response) in wildlife. Species-specific differences in glucocorticoid metabolism and excretion require assay validation, including both laboratory and biological components, before assay use in new species. We validated a commercially available radioimmunoassay (MP 125I corticosterone RIA kit MP Biomedicals, Solon, OH) for measuring FGMs of several South African herbivores, including giraffe (Giraffa camelopardalis), impala (Aepyceros melampus), nyala (Tragelaphus buxtoni), kudu (Tragelaphus strepsiceros), wildebeest (Connochaetes taurinus), and zebra (Equus burchelli). These herbivores are important in South African parks and reserves for ecotourism and as a prey base for predators and serve an integral role in ecosystem processes. Standard biochemical validations (e.g., recovery of exogenous corticosterone, intra- and interassay variation, and parallelism) demonstrated that the assay accurately and precisely measured FGMs of all 6 herbivore species. Our biological validations demonstrated that the assay was sensitive enough to detect changes in FGM production associated with season. Samples collected during the dry season (JunAug) contained higher FGM concentrations than those from the wet season (DecFeb) in all species. We established optimal sample dilutions and reference FGM levels for these 6 herbivores, which can now be used to monitor the effects of management and ecotourism activities on the stress responses of these herbivores.

Original languageEnglish
Pages (from-to)1014-1020
Number of pages7
JournalJournal of Wildlife Management
Issue number6
StatePublished - Aug 2009


  • Adrenal activity
  • Assay validation
  • Fecal glucocorticoid assay
  • Herbivore
  • Physiological stress
  • Radioimmunoassay
  • South Africa
  • Stress


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