Effect of food limitation and reproductive activity on fecal glucocorticoid metabolite levels in banded mongooses.

BACKGROUND: Glucocorticoids mediate responses to perceived stressors, thereby restoring homeostasis. However, prolonged glucocorticoid elevation may cause homeostatic overload. Using extensive field investigations of banded mongoose (Mungos mungo) groups in northern Botswana, we assessed the influence of reproduction, predation risk, and food limitation on apparent homeostatic overload (n=13 groups, 1542 samples from 268 animals). We experimentally manipulated reproduction and regulated food supply in captive mongooses, and compared their glucocorticoid responses to those obtained from free-living groups. RESULTS: At the population level, variation in glucocorticoid levels in free-living mongooses was explained by food limitation: fecal organic matter, recent rainfall, and access to concentrated anthropogenic food resources. Soil macrofauna density and reproductive events explained less and predation risk very little variation in glucocorticoid levels. Reproduction and its associated challenges alone (under regulated feeding conditions) increased glucocorticoid levels 19-fold in a captive group. Among free-living groups, glucocorticoid elevation was seasonal (occurring in late dry season or early wet season when natural food resources were less available), but the timing of peak glucocorticoid production was moderated by access to anthropogenic resources (groups with fewer anthropogenic food sources had peaks earlier in dry seasons). Peak months represented 12- and 16-fold increases in glucocorticoids relative to nadir months with some animals exhibiting 100-fold increases. Relative to the captive group nadir, some free-living groups exhibited 60-fold increases in peak glucocorticoid levels with some animals exhibiting up to 800-fold increases. Most of these animals exhibited 1- to 10-fold increases relative to the captive animal peak. CONCLUSIONS: Banded mongooses exhibit seasonal chronic glucocorticoid elevation, associated primarily with food limitation and secondarily with reproduction. Magnitude and duration of this elevation suggests that this may be maladaptive for some animals, with possible fitness consequences. In late dry season, this population may face a convergence of stressors (food limitation, agonistic encounters at concentrated food resources, evictions, estrus, mate competition, parturition, and predation pressure on pups), which may induce homeostatic overload.

Diagnostic Value of Energy Dispersive Hand-Held X-ray Fluorescence Spectrometry in Determining Trace Element Concentrations in Ovine Liver.

There are no data available on the use of hand-held X-ray fluorescence (XRF) spectrometry to determine trace element concentrations in veterinary diagnostics. The hand-held XRF spectrometer is easy to use and does not require extensive training for the operator. In Sub-Saharan Africa with few centralised analytical laboratories equipped with expensive apparatus or mass spectrometry capabilities, trace element analysis using the hand-held XRF spectrometer provides an alternative. The objective of this study was to compare ovine hepatic copper (Cu), iron (Fe), manganese (Mn), molybdenum (Mo), selenium (Se) and zinc (Zn) concentrations as obtained with the hand-held XRF spectrometer to those of a reference laboratory using inductively coupled plasma mass spectrometry (ICP-MS). Thirty ovine livers were obtained from an abattoir; prepared as wet blended and oven-dried samples and analysed. Bayesian correlation was used to assess the correspondence between results from the XRF and ICP-MS analyses. The oven-dried preparation procedure for XRF provided the best correlation with the ICP-MS data. The correlations for Cu and Zn were strong and the XRF method may represent a suitable substitute for ICP-MS analysis. For Mn and Fe the correlations were moderately strong and the XRF method may be suitable. For Mo, the correlation was weak and XRF cannot be recommended. Selenium could not be detected in samples prepared by either method. Hand-held XRF spectrometry was a practical method to determine liver concentrations of specific trace elements under African conditions and may significantly reduce the turn-around time of analysis, but unfortunately the apparatus is expensive.

Novel Mycobacterium tuberculosis complex pathogen, M. mungi.

Seven outbreaks involving increasing numbers of banded mongoose troops and high death rates have been documented. We identified a Mycobacterium tuberculosis complex pathogen, M. mungi sp. nov., as the causative agent among banded mongooses that live near humans in Chobe District, Botswana. Host spectrum and transmission dynamics remain unknown.