A field-friendly alternative to freeze-drying faeces for glucocorticoid metabolite analyses of African wild dogs (Lycaon pictus)

Postiglione, G; Accorsi, Pier Attilio; Ganswindt, André; Crossey, Bruce

doi:10.1016/j.mex.2022.101623

Cited by 5 publications

(2 citation statements)

References 13 publications

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“…We suggest that the effects of temporary storage at +4°C should also be carried out on a finer time scale to more accurately assess the kinetics of FCMs degradation. Our findings advocate and confirm that the best practice to avoid alteration of FCMs is to freeze fecal samples immediately upon collection, or alternatively, to lyophilize the samples on the field (Postiglione et al, 2022). Where this condition is not possible, similar storage experiments need to be performed on the species of interest (Palme, 2019) to access the rate of FCMs degradation at low above freezing temperatures and to improve sample preservation practices in FCMs studies.…”

Section: Discussionsupporting

confidence: 79%

Instability of fecal glucocorticoid metabolites at 4°C: Time to freeze matters

et al. 2023

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The use of fecal corticosteroid metabolites (FCMs) has proven to be well suited to evaluate adrenocortical activity, a major component of the stress response, particularly in wildlife. As with any tools, confounding factors and drawbacks must be carefully considered. Among them, sample preservation and storage are of particular importance, as they can affect stability of FCMs and lead to biased results and interpretations. Arguably, immediate freezing of fecal samples upon collection is the best practice to preserve FCM integrity, however, for logistical reasons, this condition is rarely feasible in the field. It is generally argued that temporary storage of samples at low above-zero temperature is an acceptable way of preserving samples in the field before freezing them for long-term storage.However, to our knowledge, there is no empirical study that demonstrates the stability of fecal metabolites in samples stored at +4°C. In this study, we collected a fresh fecal sample from 20 captive roe deer, each of which was homogenized and split into three subsamples (60 subsamples in total) to investigate the effects on FCMs levels of temporary storage at +4°C for 24 h and 48 h before freezing versus immediate freezing at −20°C after feces collection. Compared to immediate

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Section: Discussionsupporting

confidence: 79%

Instability of fecal glucocorticoid metabolites at 4°C: Time to freeze matters

et al. 2023

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“…Very recently, a dehydration technique using a low-power supplied food dehydrator has been tested on African wild dog faeces and has shown encouraging results on the integrity of fGCMs ( Postiglione et al, 2022 ). Compared with other alternative drying processes, such as exposure to sunlight and the solar oven, this protocol fastens the removal of moisture from the faeces by combining heating with the circulation of a constant air flow.…”

Section: Introductionmentioning

confidence: 99%

Validation of a field-friendly faeces drying and storage method for quantifying faecal glucocorticoid metabolites in African elephants (Loxodonta africana) opens up new perspectives for conservationists

Lacomme,

Guerbois,

Fritz

et al. 2023

Conservation Physiology

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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 (R2 = 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; P = 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.

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