Significantly higher (P<0.002) than the dry season (mean 2.59 micrograms/gram dry
Significantly higher (P<0.002) than the dry season (mean 2.59 micrograms/gram dry faeces).(Continued on next page)* Correspondence: [email protected] 1 Department of Production Animal Studies, Faculty of Veterinary Science, University of Pretoria, Onderstepoort, RSA Full list of author information is available at the end of the article?2012 Benavides Valades et al.; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any PubMed ID:http://www.ncbi.nlm.nih.gov/pubmed/27766426 medium, provided the original work is properly cited.Benavides Valades et al. Reproductive Biology and Endocrinology 2012, 10:63 http://www.rbej.com/content/10/1/Page 2 of(Continued from previous page)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 CPI-455 site 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. Keywords: GnRH immunocontraception, African elephant cows, Oestrous cycle, Non-invasive monitoring, Faecal progestagen metabolites, Ecological effectsBackground In southern Africa the savannah elephants (Loxodonta africana) began recovering in numbers after the banning of the ivory trade in 1990. Currently 70 of Africa’s elephants occur in southern Africa with an annual rate of increase of 4-5 [1-3]. Many of the smaller elephant populations (<1000 elephants) are held in fenced reserves. The space constraint imposed by the fencing results in: limiting natural behaviour [4], habitat degradation with a consequent negative impact on the many species that share the same space, conflict with human communities that border conservation areas and the possibility of population crashes [5,6]. Elephants are considered to be non-seasonal, polyoestrus and uniparous breeders [7]; although there is a peak in conception rates and births during the rainy season, when resources are more abundant [8-11]. In captive elephants the duration of the oestrous cycle length is 13 to 17 weeks [12]. It consists of a luteal phase (LP) lasting 6 to 12 weeks with elevated levels of progestagens and an inter-luteal or follicular phase (ILP) ranging from 4 to 6 weeks [7,13]. Oestrus with typical behavioural signs lasts 2 to 8 days [14,15]. Several options are being practiced or considered to mitigate the overpopulation problem. These include culling, range expansion through establishment of cross-border protected areas and protection of migration corridors, translocation to under-populated areas and fertility control [16,17]. Among the PubMed ID:https://www.ncbi.nlm.nih.gov/pubmed/26024392 available fertility control options, immunocontraception using native porcine zona pellucida (pZP) proteins seems to be the most viable means of population management for smaller and confined populations of elephants [18]. A possible disadvantage of pZPimmunocontraception is that treated females continue to cycle normally, approximately every 15 weeks [19] and continuously attract bulls which could potentially disrupt the herd [20]. An additional potentially-promising option for fertility control of free-ranging animals is immunization against GnRH. This has been safely and effectively used in.