Lacomme Laura, Guerbois Chloé, Fritz Hervé, Ganswindt André, Rey Benjamin
REHABS International Research Laboratory, French National Centre for Scientific Research (CNRS), University of Lyon 1, Nelson Mandela University, Madiba Drive, George 6529, South Africa.
Mammal Research Institute (MRI), Department of Zoology and Entomology, Faculty of Natural and Agricultural Sciences, University of Pretoria, Hatfield Campus, Pretoria 0028, South Africa.
Conserv Physiol. 2023 Jul 31;11(1):coad053. doi: 10.1093/conphys/coad053. eCollection 2023.
Faecal glucocorticoid metabolites (fGCMs) are a relevant means of non-invasively assessing adrenocortical activity and thus, a key physiological stress response in wildlife populations. However, the widespread use of fGCMs as a stress-related biomarker in conservation biology is often hampered by the logistical challenge of storing collected faecal material frozen until it reaches the laboratory for analysis. Although alternative approaches to minimize potential alteration of fGCM composition post-defecation have been recently identified, there is to our knowledge, no satisfactory alternative method established for the preservation of elephant dung. In this study, we validated a field-friendly protocol for dehydrating African elephant faeces samples using a food dehydrator with desiccant and investigated the stability of fGCM concentrations in the dehydrated faeces when stored at ambient temperature. We collected 40 faecal samples from African elephants and compared fGCM concentrations of freeze-dried and dehydrated sample sub-sets. Samples dried in the field showed a slight but significant overall -6% reduction in fGCM concentration compared with frozen control samples. However, fGCM concentrations following field dehydration protocol match those of control samples with high accuracy, as evidenced by the low bias and strong coefficient of determination between the two approaches (R = 0.88). In addition, over nearly 2 months, storage time at ambient temperature of the dehydrated samples had no effect on the fGCM concentrations compared with those measured in the control samples (F-statistic = 1.82; = 0.18). Dehydrating the samples in the field thus provides an easy and cost-effective alternative to freezing, especially when working in remote areas with unstable electrical supply. Our results encourage the widespread use of fGCMs by conservationists as non-invasive means of steroid monitoring of African elephants in the current context of a general increase in wildlife welfare research. Future studies are needed to extend the use of this protocol to other species and to other steroid classes.
粪便糖皮质激素代谢物（fGCMs）是一种非侵入性评估肾上腺皮质活动的相关手段，因此也是野生动物种群关键的生理应激反应。然而，在保护生物学中，将fGCMs广泛用作与应激相关的生物标志物，常常受到后勤挑战的阻碍，即需要将收集到的粪便材料冷冻保存，直到送到实验室进行分析。尽管最近已经确定了一些替代方法，以尽量减少排便后fGCMs成分的潜在变化，但据我们所知，尚未建立一种令人满意的保存大象粪便的替代方法。在本研究中，我们验证了一种便于野外操作的方案，即使用带有干燥剂的食品脱水机对非洲象粪便样本进行脱水，并研究了脱水粪便在室温下储存时fGCMs浓度的稳定性。我们从非洲象身上收集了40份粪便样本，并比较了冻干和脱水样本子集的fGCMs浓度。与冷冻对照样本相比，在野外干燥的样本中fGCM浓度总体略有但显著降低了6%。然而，野外脱水方案后的fGCM浓度与对照样本的浓度高度匹配，这两种方法之间的低偏差和强决定系数（R = 0.88）证明了这一点。此外，在近两个月的时间里，脱水样本在室温下的储存时间对fGCM浓度没有影响，与对照样本中测得的浓度相比（F统计量 = 1.82；P = 0.18）。因此，在野外对样本进行脱水提供了一种简单且经济高效的冷冻替代方法，特别是在电力供应不稳定的偏远地区工作时。我们的结果鼓励保护主义者在当前野生动物福利研究普遍增加的背景下，广泛使用fGCMs作为对非洲象进行类固醇监测的非侵入性手段。未来的研究需要将该方案的应用扩展到其他物种和其他类固醇类别。
