Comparison of different drying and storage methods on quantifiable concentrations of fecal steroids in the cheetah

Publication Type:
 Journal Article
Year of Publication:
 2002
Authors:
 Karen A. Terio, Janine L. Brown, Rachel Moreland, Linda Munson
Publication/Journal:
 Zoo Biology
Publisher:
 A Wiley Company, Inc., Wiley Subscription Services
Keywords:
 , , , ,
ISBN:
 1098-2361
Abstract:

Abstract 10.1002/zoo.10036.abs Fecal steroid analysis is a powerful tool that can provide important information on the health, physiology, and reproductive status of nondomestic species. However, studying free-ranging animals requires that feces be stored and transported from the collection site to the laboratory in a manner that prevents degradation or alteration of steroid metabolites. To determine the effects of different handling and storage methods on fecal steroids, 30 fresh fecal samples from five captive cheetahs were collected, thoroughly mixed, separated into aliquots, and processed (stored or dried) under different conditions. Concentrations of gonadal and adrenal steroid hormones were analyzed in feces stored frozen at –20°C or at room temperature in 95% ethanol. Both frozen and ethanol-stored aliquots were desiccated using a lyophilizer, solar oven, or conventional oven. The steroid values from aliquots stored and desiccated using the different methods were compared to those obtained using the optimal storage method of freezing at –20°C and desiccating in a lyophilizer (control). Concentrations of corticoid, estrogen, progestagen, and androgen metabolites in fecal extracts were quantified by radioimmunoassay. Androgen metabolite concentrations were not significantly affected (P > 0.05) by storage or drying methods. Fecal samples stored at room temperature in ethanol and lyophilized also had steroid concentrations that did not differ (P > 0.05) from controls. However, the concentrations of corticoid and estrogen metabolites were significantly lower (P < 0.05), and progestagen metabolites were significantly higher (P < 0.05) in samples desiccated in solar and conventional ovens without regard to storage method. These results suggest that storage of fecal samples at room temperature in ethanol is the best alternative to freezing for subsequent analysis of steroid hormone concentrations. Differences in measured concentrations of hormones in oven-desiccated samples could be due to hormone degradation or shifts in the immunodominant metabolite. Therefore, validation of storage and processing techniques should be included in the development of any new fecal steroid analysis methodology. Zoo Biol 21:215–222, 2002. © 2002 Wiley-Liss, Inc.

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