Vaccination against GnRH may suppress aggressive behaviour and musth in African elephant (Loxodonta africana) bulls - a pilot study

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

EFFECTS OF A GONADOTROPIN-RELEASING HORMONE VACCINE ON OVARIAN CYCLICITY AND UTERINE MORPHOLOGY OF AN ASIAN ELEPHANT (ELEPHAS MAXIMUS)

“…17,19,20,40,41,48,54 Preliminary evaluation of a GnRH vaccine for control of aggression and musth behavior in bull elephants has shown some degree of variation in the response of individuals, and this phenomenon has been noted in a variety of other species. 2,13,23,30,32,52 More work clearly is needed to optimize the dose and frequency of vaccination when using the Repro-BLOC formulation in elephants, because it took more than a year for the effects to be realized. It is not clear why this elephant required multiple boosters before the desired effect of vaccination occurred.…”

“…3,18,30,36,41,43 In elephant bulls, GnRH vaccination has shown efficacy in suppressing testosterone production and musth behaviors, presumably by similarly inhibiting pituitary control of gonadal steroidogenic activity. 2,13,14 A carefully managed contraception strategy would be of particular value in areas of high elephant density in close proximity to humans to mitigate human-elephant conflicts and in game parks where protected space and resources are limited. It would be beneficial to compare the efficacy, duration of effect, reversibility, longterm health and genetic effects, and social and behavioral effects of GnRH vaccination in elephants with those of porcine zona pellucida vaccination, which prevents fertilization by blocking sperm binding to the egg and is currently used in female elephants for contraception.…”

Concentrations of faecal glucocorticoid metabolites in physically injured free‐ranging African elephants Loxodonta africana

“…For African elephants in zoos as well as in the wild, these methods have been shown to be practical and enable long-term monitoring of environmental and social factors impacting on adrenocortical activity without interfering with the result (Ganswindt et al 2005a,b, Rasmussen et al 2008, Ganswindt et al 2010. In this regard, several studies demonstrated that extrinsic and intrinsic factors like translocation, seasonal variation, intra-group competition or sexual state can affect glucocorticoid levels in African elephants (Foley et al 2001, Ganswindt et al 2005a,b, Viljoen et al 2008a,b, Ganswindt et al 2010, De Nys et al 2010. For various reasons, the relationship between adrenal activity and physical injuries is less documented.…”

Castration of male livestock and the potential of immunocastration to improve animal we

“…Castration is not limited to use in livestock species, but also finds application in companion animals, horses maintained for recreational purposes, and, more recently, wildlife (De Nys et al, 2010). The typical purpose of castration is to ease handling and management by controlling sexual and aggressive behaviour.…”

“…Immunocastration was used in both stallions and mares (Garza et al, 1988) to suppress reproduction, with the first successful report of its use in stallions (Schanbacher & Pratt, 1985). Immunocastration also showed promise to control aggressive behaviour in wild and captive African elephants by successfully decreasing androgen production (De Nys et al, 2010). Research into immunocastration of primates indicated that an increased GnRH-antibody titre and decreased testosterone production were associated with a reduced prostate weight (Giri et al, 1991).…”