Measuring Faecal Glucocorticoid Metabolite Concentrations as an Indicator of Stress in Blue Wildebeest (Connochaetes taurinus)

Abstract

In South Africa, blue wildebeest (Connochaetes taurinus) are routinely captured for relocation purposes. To monitor the stress caused by this practise, a non-invasive method assessing adrenocortical function as a measure of stress would minimize disturbance during sample collection. In our study, an adrenocorticotropic hormone challenge, and a mass-capture event were used to examine the suitability of five enzyme immunoassays (EIAs) for monitoring stress-related physiological responses using faeces as a sample matrix. The tested 11-oxoaetiocholanolone I EIA performed best, showing a 2126% increase above baseline after 22 h for a male, and a 474% increase for a female 23 h post-ACTH injection. Baseline faecal glucocorticoid metabolite (fGCM) concentrations did not differ between animals captured on either day 1 or day 2 of the capture event, indicating that the frequent presence of a helicopter during the two days did not influence fGCM concentrations. However, during capture-related restraint for up to 10 h, an overall 1.5-fold elevation in (fGCM) concentrations was found. Storage of faeces at ambient temperature post-defecation indicated a fair stability of fGCMs for up to 8 h. The ability to reliably assess adrenocortical function provides a solid basis to examine endocrine responses to putative stressful circumstances in blue wildebeest.

Validation of Fecal Glucocorticoid Metabolites as Non-Invasive Markers for Monitoring Stress in Common Buzzards (Buteo buteo)

“…In contrast to many other studies, we did not find significant differences in the baseline glucocorticoid levels or stress responses between females and males. In rats [70], chickens [31], Puerto Rican Parrots [58], Northern Spotted Owls [35,37], Blue Wildebeest [71], and Sea Lions [72], males tend to have significantly higher baseline values or stress responses than females. However, in mice [73], hares [74], and African Wild Dogs [75], females tend to have higher baseline glucocorticoid concentrations compared to males.…”

“…Bacterial enzymes can cause the fGCM concentration in feces to continue to rise or fall after a certain time [14,88]. In White-tailed Sea Eagles, the stability of urine GCM concentration lasted for 9 days [43], in the Nile Crocodile the fGCM concentration in feces remained stable for 72 h at ambient temperature [89], while in Grey Mouse Lemurs it remained stable for at least 10 h [64], in Cheetahs for 22 h at 0-4 • C [90], in Blue Wildebeest for 8 h [71], and in Leopards even up to 6 days post-defecation [91]. In the present study, glucocorticoid concentrations remained relatively stable with a variation of up to 18% within the first 4 h. After that, the measured concentration dropped significantly in the 8 h subset.…”