Abstract
Aggressive behaviour and musth are constant problems in captive and sometimes in free-ranging African elephant bulls. Aggressive bulls are difficult and musth bulls almost impossible to manage without severely restricting their movement either by leg-chaining or using tranquillisers. This study investigated the relationship between faecal androgen metabolites (FAM) and faecal cortisol metabolites (FCM) concentrations and aggressive behaviour and tested a GnRH vaccine as a means of down-regulating aggressive behaviour and musth in 1 free-ranging and 5 captive elephant bulls. The bulls were non-aggressive (n=3), aggressive (n=2) or in musth (n=1) at the onset of the study. The bulls were injected with a GnRH vaccine-adjuvant combination 3 or 4 times at 3- to 7-week intervals. Behaviour, FAM and FCM concentrations were measured during every week prior to vaccination until 4 months after the last vaccination. FAM concentrations were positively correlated with aggressive behaviour before the 1st vaccination. Androgen production, as reflected by FAM concentrations, was down-regulated in 3 of the 6 immunised bulls. At least 2 bulls and possibly a 3rd showed behavioural improvement following GnRH vaccination and in all 3 temporal gland secretion ceased. No further aggressive behaviour was observed until the end of the study in any of the bulls. The results of this 1st GnRH immunisation study suggest that it could be a useful method to control aggressive behaviour and musth in African elephant bulls.
Highlights
Musth, a condition exhibited periodically by adult male elephants[43], is associated with increased aggressive behaviour[11,41,43] and creates serious problems in the management of captive and free-ranging elephant bulls
There were no significant correlations between Faecal androgen metabolites (FAM) and faecal cortisol metabolites (FCM) in Kinkel, Thembo, Toto and Grootvoet whereas positive correlations were found for Chaka (r = 0.51; P < 0.05) and Makavhuzi (r = 0.48; P < 0.05). This is the 1st study that reports the use of a gonadotrophin releasing hormone (GnRH) vaccine to attempt downregulation of musth or aggressive behaviour in African elephant bulls
When non-musth bulls were divided into aggressive (Thembo and Kinkel) and non-aggressive groups (Toto, Chaka and Makavhuzi) during Stage 1, behaviour was well correlated to FAM concentration
Summary
A condition exhibited periodically by adult male elephants[43], is associated with increased aggressive behaviour[11,41,43] and creates serious problems in the management of captive and free-ranging elephant bulls. Such bulls may even endanger the lives of both animals and humans. Apart from increased aggressive behaviour, the main signs of musth are heavy and continuous temporal gland secretion (TGS) and continuous aSection of Reproduction, Department of Production Animal Studies, Faculty of Veterinary Science, University of Pretoria, Private Bag X04, Onderstepoort, 0110 South Africa. CFaculty of Veterinary Medicine, Utrecht University Yalelaan 1, 3584 CL Utrecht, Netherlands.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
