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Non-invasive assessment of adrenocortical function in captive Nile crocodiles (Crocodylus niloticus)


Ganswindt, SB and Myburgh, JG and Cameron, EZ and Ganswindt, A, Non-invasive assessment of adrenocortical function in captive Nile crocodiles (Crocodylus niloticus), Comparative Biochemistry and Physiology Part A, 177 pp. 11-17. ISSN 1095-6433 (2014) [Refereed Article]

Copyright Statement

Copyright 2014 Elsevier Inc.

DOI: doi:10.1016/j.cbpa.2014.07.013


The occurrence of stress-inducing factors in captive crocodilians is a concern, since chronic stress can negatively affect animal health and reproduction, and hence production. Monitoring stress in wild crocodiles could also be beneficial for assessing the state of health in populations which are potentially threatened by environmental pollution. In both cases, a non-invasive approach to assess adrenocortical function as a measure of stress would be preferable, as animals are not disturbed during sample collection, and therefore sampling is feedback-free. So far, however, such a non-invasive method has not been established for any crocodilian species. As an initial step, we therefore examined the suitability of two enzyme-immunoassays, detecting faecal glucocorticoid metabolites (FGMs) with a 11β,21-diol-20-one and 5β-3α-ol-11-one structure, respectively, for monitoring stress-related physiological responses in captive Nile crocodiles (Crocodylus niloticus). An adrenocorticotropic hormone (ACTH) challenge was performed on 10 sub-adult crocodiles, resulting in an overall increase in serum corticosterone levels of 272% above the pre-injection levels 5 h post-injection. Saline-treated control animals (n = 8) showed an overall increase of 156% in serum corticosterone levels 5 h post-administration. Faecal samples pre- and post-injection could be obtained from three of the six individually housed crocodiles, resulting in FGM concentrations 136380% above pre-injection levels, always detected in the first sample collected post-treatment (715 days post-injection). FGM concentrations seem comparatively stable at ambient temperatures for up to 72 h post-defaecation. In conclusion, non-invasive hormone monitoring can be used for assessing adrenocortical function in captive Nile crocodiles based on FGM analysis.

Item Details

Item Type:Refereed Article
Keywords:stress physiology, management, ACTH challenge test, adrenocortical function, corticosterone, enzyme-immunoassay, faecal glucocorticoid metabolites, Nile crocodile, post-defaecation hormone stability
Research Division:Biological Sciences
Research Group:Ecology
Research Field:Behavioural ecology
Objective Division:Environmental Management
Objective Group:Terrestrial systems and management
Objective Field:Terrestrial biodiversity
UTAS Author:Cameron, EZ (Professor Elissa Cameron)
ID Code:93769
Year Published:2014
Web of Science® Times Cited:13
Deposited By:Zoology
Deposited On:2014-08-15
Last Modified:2017-10-31

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