Validation of Fecal Glucocorticoid Metabolite Assays for South African Herbivores

Authors

  • SATHYA K. CHINNADURAI,

    1. Department of Fisheries and Wildlife Sciences, University of Missouri, 302 Natural Resources Building, Columbia, MO 65211, USA
    Search for more papers by this author
    • Department of Clinical Sciences, College of Veterinary Medicine, North Carolina State University, 4700 Hillsborough Street, Raleigh, NC 27606, USA

  • JOSHUA J. MILLSPAUGH,

    Corresponding author
    1. Department of Fisheries and Wildlife Sciences, University of Missouri, 302 Natural Resources Building, Columbia, MO 65211, USA
    Search for more papers by this author
  • WAYNE S. MATTHEWS,

    1. Ezemvelo KwaZulu-Natal Wildlife, Tembe Elephant Park, Private Bag X356, KwaNgwanase 3973, South Africa
    Search for more papers by this author
  • KIRSTEN CANTER,

    1. School of Biological and Conservation Sciences, University of KwaZulu-Natal, Durban 4041, South Africa
    Search for more papers by this author
  • ROB SLOTOW,

    1. School of Biological and Conservation Sciences, University of KwaZulu-Natal, Durban 4041, South Africa
    Search for more papers by this author
  • BRIAN E. WASHBURN,

    1. United States Department of Agriculture, Wildlife Services, National Wildlife Research Center, 6100 Columbus Avenue, Sandusky, OH 44870, USA
    Search for more papers by this author
  • RAMI J. WOODS

    1. Department of Fisheries and Wildlife Sciences, University of Missouri, 302 Natural Resources Building, Columbia, MO 65211, USA
    Search for more papers by this author

MillspaughJ@missouri.edu

Abstract

ABSTRACT  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 (Jun-Aug) contained higher FGM concentrations than those from the wet season (Dec-Feb) 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.

Ancillary