Journal article
Non-invasive assessment of the reproductive cycle in free-ranging female African elephants (Loxodonta africana) treated with a gonadotropin-releasing hormone (GnRH) vaccine for inducing anoestrus
Reproductive Biology and Endocrinology, Vol.10(1), Article number: 63
2012
Abstract
Background
In southern Africa, various options to manage elephant populations are being considered. Immunocontraception is considered to be the most ethically acceptable and logistically feasible method for control of smaller and confined populations. In this regard, the use of gonadotropin-releasing hormone (GnRH) vaccine has not been investigated in female elephants, although it has been reported to be safe and effective in several domestic and wildlife species. The aims of this study were to monitor the oestrous cycles of free-ranging African elephant cows using faecal progestagen metabolites and to evaluate the efficacy of a GnRH vaccine to induce anoestrus in treated cows.
Methods
Between May 2009 - June 2010, luteal activity of 12 elephant cows was monitored non-invasively using an enzyme immunoassay detecting faecal 5alpha-reduced pregnanes (faecal progestagen metabolites, FPM) on a private game reserve in South Africa. No bulls of breeding age were present on the reserve prior to and for the duration of the study. After a 3-month control period, 8 randomly-selected females were treated twice with 600 micrograms of GnRH vaccine (Improvac®, Pfizer Animal Health, Sandton, South Africa) 5-7 weeks apart. Four of these females had been treated previously with the porcine zona pellucida (pZP) vaccine for four years (2004-2007).
Results
All 12 monitored females (8 treated and 4 controls) showed signs of luteal activity as evidenced by FPM concentrations exceeding individual baseline values more than once. A total of 16 oestrous cycles could be identified in 8 cows with four of these within the 13 to 17 weeks range previously reported for captive African elephants. According to the FPM concentrations the GnRH vaccine was unable to induce anoestrus in the treated cows. Overall FPM levels in samples collected during the wet season (mean 4.03 micrograms/gram dry faeces) were significantly higher (P<0.002) than the dry season (mean 2.59 micrograms/gram dry faeces).
Conclusions
The GnRH vaccination protocol failed to induce anoestrus in the treated female elephants. These results indicate that irregular oestrous cycles occur amongst free-ranging elephants and are not restricted to elephants in captivity. The relationship between ecological conditions and endocrine activity were confirmed. Free-ranging female elephants were observed to not cycle continuously throughout the year in the absence of adult bulls.
Details
- Title
- Non-invasive assessment of the reproductive cycle in free-ranging female African elephants (Loxodonta africana) treated with a gonadotropin-releasing hormone (GnRH) vaccine for inducing anoestrus
- Authors/Creators
- G. Benavides Valades (Author/Creator)A. Ganswindt (Author/Creator) - Onderstepoort Veterinary Academic HospitalH. Annandale (Author/Creator) - Onderstepoort Veterinary Academic HospitalM.L. Schulman (Author/Creator) - Onderstepoort Veterinary Academic HospitalH.J. Bertschinger (Author/Creator) - Onderstepoort Veterinary Academic Hospital
- Publication Details
- Reproductive Biology and Endocrinology, Vol.10(1), Article number: 63
- Publisher
- BMC
- Identifiers
- 991005543551807891
- Copyright
- © 2012 Benavides Valades et al.
- Murdoch Affiliation
- Murdoch University
- Language
- English
- Resource Type
- Journal article
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- Citation topics
- 3 Agriculture, Environment & Ecology
- 3.35 Zoology & Animal Ecology
- 3.35.693 Primate Behavior
- Web Of Science research areas
- Endocrinology & Metabolism
- Reproductive Biology
- ESI research areas
- Biology & Biochemistry