The tail-tale of stress: an exploratory analysis of cortisol levels in the tail-hair of captive Asian elephants

Pokharel, SS and Yoneda, H and Yanagi, M and Sukumar, R and Kinoshita, K (2021) The tail-tale of stress: an exploratory analysis of cortisol levels in the tail-hair of captive Asian elephants. In: PeerJ, 9 .

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Abstract

Background. Assessment of physiological states by measuring biomarkers, such as cortisol, has significantly contributed to the monitoring of health, welfare and management of animals. Immunoreactive cortisol in hair (hC) has been used widely for deciphering ‘stressful’ past-events in various wild and captive animals. However, no such studies have been done in long-lived mammals. Methods. In this first exploratory study in elephants, we assessed (i) tail-hair growth rate (TGR) and (ii) hC levels in tail-hair samples from six captive Asian elephants from two zoos in Japan for comparing hC levels with zoo-keepers’ records of distinct biological events over a c.0.5–2.0-year period. Tail-hair samples were cut into segments (based on monthly growth rate), pulverized or minced and a validated cortisol enzyme-immunoassay employed to measure hC levels. Results. When the hC levels of all individuals were compared with the keepers’ records, a posteriori, most of the high hC levels were found to be associated with ‘stressful’ or distinct behavioural events such as pathological (anaemia, colic infection, skin infection, oral sores), psychosocial (reluctance in entering the enclosure, presence of a calf) and husbandry practice-related (contact trials/ space sharing) conditions, indicating that tail-hair indeed can be a potential ‘retrospective’ calendar of physiological health of an animal. Conclusions. Our observations open up the possibility of using the tail-hair as an alternative matrix to reconstruct the physiological history of elephants. Copyright 2021 Pokharel et al.

Item Type:	Journal Article
Publication:	PeerJ
Publisher:	PeerJ Inc.
Additional Information:	The copyright for this article belongs to the PeerJ Inc.
Keywords:	Asian elephant; Elephas maximus; Hair cortisol; Stress; Stress physiology; Tail hair
Department/Centre:	Division of Biological Sciences > Centre for Ecological Sciences
Date Deposited:	14 Jul 2023 06:15
Last Modified:	14 Jul 2023 06:15
URI:	https://eprints.iisc.ac.in/id/eprint/81808

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