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Non-invasive assessment of adrenocortical function in captive Nile crocodiles (Crocodylus niloticus) and its relation to housing conditions
Dissertation (MSc)--University of Pretoria, 2012.
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University of Pretoria
2013
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| _version_ | 1867613682223022080 |
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| access_status_str | Open Access |
| author2 | Myburgh, Jan G. |
| author_browse | Myburgh, Jan G. |
| author_facet | Myburgh, Jan G. |
| collection | Thesis |
| dc_rights_str_mv | © 2012 University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria |
| description | Dissertation (MSc)--University of Pretoria, 2012. |
| format | Thesis |
| id | oai:repository.up.ac.za:2263/25143 |
| institution | University of Pretoria (South Africa) |
| last_indexed | 2026-06-10T12:40:01.664Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from UPSpace — University of Pretoria Institutional Repository |
| publishDate | 2013 |
| publishDateRange | 2013 |
| publishDateSort | 2013 |
| publisher | University of Pretoria |
| publisherStr | University of Pretoria |
| record_format | dspace |
| source_str | UPSpace — University of Pretoria Institutional Repository |
| spelling | oai:repository.up.ac.za:2263/25143 Non-invasive assessment of adrenocortical function in captive Nile crocodiles (Crocodylus niloticus) and its relation to housing conditions Myburgh, Jan G. Cameron, Elissa Z. stefanie.ganswindt@up.ac.za Ganswindt, Stefanie Birgit Southern Africa Nile crocodile (Crocodylus niloticus) Crocodilian species UCTD Dissertation (MSc)--University of Pretoria, 2012. The Nile crocodile (Crocodylus niloticus) is one of 23 extant crocodilian species, and has been farmed in southern Africa since the 1960s. For the crocodile industry, chronic stress and its often negative consequences are a concern, since stressors can negatively affect animal production as well as the health of the crocodiles. When confronted with a stressor, an individual displays a stress response consisting of a suite of physiological and behavioral alterations to cope with the challenge. So far, however, no method for determining stress-related responses in Nile crocodiles has been established. In other crocodilians, the assessment of physiological responses to stress, like the related alterations in glucocorticoid concentrations, has already been done, but only by using an invasive approach, with the disadvantage of a possible handling-induced stress response. By establishing a non-invasive technique to monitor glucocorticoid levels in captive Nile crocodiles based on faecal hormone analysis, this study not only made an important contribution to a better understanding of stress and related hormonal changes in Nile crocodiles, but also provided a solid basis for developing similar non-invasive tools to collect information on the level of stress experienced by other crocodilians. Specifically the study aimed 1) to assess adrenocortical activity in Nile crocodiles by measuring faecal glucocorticoid metabolite (FGM) concentrations, and 2) to characterise changes in FGM levels in captive Nile crocodiles in relation to different housing conditions. An adrenocorticotropic hormone (ACTH) challenge was performed on 10 sub-adult crocodiles at Le Croc crocodile farm, South Africa, resulting in serum corticosterone levels of up to ~1200 %, 1 - 5 hours post-injection, above the pre-injection levels. An additional 8 individuals were exposed to electric immobilisation and handling only (control group), which resulted in a 20 – 2700 % elevation in serum corticosterone concentrations, indicating that handling was already a sufficient stressor. FGM levels in 3 singly housed animals (2 ACTH challenge; 1 handling only) reached peaks of 136 – 380 % above pre-injection levels at about 7 to 15 days following treatment, demonstrating that non-invasive hormone monitoring can be used for assessing adrenocortical function in captive Nile crocodiles based on FGM analysis. By assessing the impact of group size (n = 1, 2, or 4 individuals) on FGM levels, highest mean hormone values were found in the paired animals. A possible explanation for this finding could be that the necessary re-grouping for the study resulted in an unstable group composition, especially for the paired animals of similar size, which is reflected in comparable higher FGM concentrations. However, future research would be necessary to investigate this potential relationship in more detail. My study created opportunities to improve the management and welfare of farmed crocodiles in terms of more appropriate housing conditions and husbandry for these animals. Finally, the now established non-invasive method for monitoring adrenocortical function in Nile crocodiles provides a solid basis for further studies focusing on monitoring factors influencing adrenocortical function in populations of Nile crocodiles in the wild. Paraclinical Sciences unrestricted 2013-09-06T19:28:41Z 2013-06-10 2013-09-06T19:28:41Z 2013-04-12 2012 2013-05-30 Dissertation Ganswindt, SB 2012, Non-invasive assessment of adrenocortical function in captive Nile crocodiles (Crocodylus niloticus) and its relation to housing conditions, MSc dissertation, University of Pretoria, Pretoria, viewed yymmdd < http://hdl.handle.net/2263/25143 > E13/4/663/gm http://hdl.handle.net/2263/25143 http://upetd.up.ac.za/thesis/available/etd-05302013-125730/ © 2012 University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria application/pdf University of Pretoria |
| spellingShingle | Southern Africa Nile crocodile (Crocodylus niloticus) Crocodilian species UCTD Non-invasive assessment of adrenocortical function in captive Nile crocodiles (Crocodylus niloticus) and its relation to housing conditions |
| title | Non-invasive assessment of adrenocortical function in captive Nile crocodiles (Crocodylus niloticus) and its relation to housing conditions |
| title_full | Non-invasive assessment of adrenocortical function in captive Nile crocodiles (Crocodylus niloticus) and its relation to housing conditions |
| title_fullStr | Non-invasive assessment of adrenocortical function in captive Nile crocodiles (Crocodylus niloticus) and its relation to housing conditions |
| title_full_unstemmed | Non-invasive assessment of adrenocortical function in captive Nile crocodiles (Crocodylus niloticus) and its relation to housing conditions |
| title_short | Non-invasive assessment of adrenocortical function in captive Nile crocodiles (Crocodylus niloticus) and its relation to housing conditions |
| title_sort | non invasive assessment of adrenocortical function in captive nile crocodiles crocodylus niloticus and its relation to housing conditions |
| topic | Southern Africa Nile crocodile (Crocodylus niloticus) Crocodilian species UCTD |
| url | http://hdl.handle.net/2263/25143 http://upetd.up.ac.za/thesis/available/etd-05302013-125730/ |