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

Carbillet, Jeffrey; Palme, Rüpert; Maublanc, Marie‐Line; Cebe, Nicolas; Gilot‐Fromont, Emmanuelle; Verheyden, Hélène; Rey, Benjamin

doi:10.1002/jez.2704

Cited by 3 publications

(1 citation statement)

References 49 publications

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“…Faeces were frozen at −20°C within 24 h prior to 2013 in CH and 2017 in TF, and immediately frozen at −80°C after collection since then. The time between faecal sampling and freezing, as well as freezing temperature, may impact FGM values, with longer delays and higher temperature likely to result in lower FGM levels due to bacterial activity (Lexen et al 2008, Hadinger et al 2015, Carbillet et al 2023b). In CH, the first FGM values available in our dataset are post‐2013, so all samples were immediately frozen at −80°C.…”

Section: Methodsmentioning

confidence: 99%

Glucocorticoids negatively relate to body mass on the short‐term in a free‐ranging ungulate

Lalande

Gilot‐Fromont

Carbillet

et al. 2023

Oikos

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Environmental fluctuations force animals to adjust glucocorticoids (GCs) secretion and release to current conditions. GCs are a widely used proxy of an individual stress level. While short‐term elevation in GCs is arguably beneficial for fitness components, previous studies have documented that the relationship between long‐term baseline GCs elevation and fitness components can vary according to ecological and individual factors and according to the life‐history of the species studied. Using longitudinal data on roe deer Capreolus capreolus from two populations facing markedly different environmental contexts, we tested whether baseline GC levels negatively correlate with body mass – a trait positively associated with demographic individual performance – on the short‐ to long‐term. In support, higher baseline GC concentrations were associated to lighter body mass, both measured during the same capture event, in adults of both populations. Overall, we showed that despite the marked environmental and demographic differences between populations and despite the between‐sex differences in life history (i.e. reproductive tactics), the relationship between body mass and GCs is consistent across environmental contexts, but might differ according to the life history stage of an individual. This work opens promising perspectives to further explore the relationship between GC and fitness‐related traits according to life history stages in free‐ranging mammals across seasonal and environmental contexts. The timing and context‐dependence of GC levels highlight the complexity of studying stress responses in the wild.

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Section: Methodsmentioning

confidence: 99%

Glucocorticoids negatively relate to body mass on the short‐term in a free‐ranging ungulate

Lalande

Gilot‐Fromont

Carbillet

et al. 2023

Oikos

Self Cite

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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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Glucocorticoids negatively relate to body mass on the short-term in a free-ranging ungulate

Lalande

Gilot‐Fromont

Carbillet

et al. 2022

Preprint

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Environmental fluctuations force animals to adjust glucocorticoids (GCs) secretion and release to current conditions. GCs are a widely used proxy of an individual stress level. While short-term elevation in GCs is arguably beneficial for fitness components, previous studies have documented that the relationship between long-term baseline GCs elevation and fitness components is largely inconsistent. Using longitudinal data on roe deer (Capreolus capreolus) from two populations with markedly different environmental contexts, we tested whether baseline GC levels negatively correlate with body mass - a trait positively associated with demographic individual performance - on the short- to long-term. In support, higher baseline GC concentrations were associated to lighter body mass, both measured during the same capture event, in juvenile and adult males of both populations. We also found evidence of a stronger association between higher GC levels and lower body mass for males born in poor years. GCs were not related to body mass neither on the long-term, nor in females of neither population. We propose that the sex-specific association between GCs and body mass are consistent between populations and regulated by environmental conditions at a finer-scale, and are driven by sex-specific life histories. The sex- and context-dependent responses of stress highlight the complexity of studying stress in the wild.

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

Cited by 3 publications

References 49 publications

Glucocorticoids negatively relate to body mass on the short‐term in a free‐ranging ungulate

Glucocorticoids negatively relate to body mass on the short‐term in a free‐ranging ungulate

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

Glucocorticoids negatively relate to body mass on the short-term in a free-ranging ungulate

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