Abstract:Because fecal samples can be collected without capturing and restraining animals, or disturbing animal behaviors, measurement of metabolites of steroid hormones by using feces has become very popular during the past decades, and it is currently being used in many areas of zoological research including wildlife conservation, behavioral ecology and physiological ecology. It is difficult to carry out direct physiological monitoring of Przewalski′s Gazelle (Procapra przewalskii) due to its particularity of population and behavior, so it is necessary to use the non-invasive sampling method to monitor the fecal steroids. We thus conducted this research to determine the effects of different storage temperatures on fecal cortisol in Przewalski′s gazelle. Fresh fecal samples were collected, thoroughly mixed and separated into 30 aliquots. Ten aliquots of mixed fecal samples were stored at ﹣20 ℃, 4 ℃ and 20 ℃, respectively. The cortisol concentrations in the samples were measured using ELISA on day 2, 5, 7, 10, 15, 20, 25, 30 and 50, respectively. The results of One-way ANOVA indicated no significant changes in the cortisol concentrations of the fecal samples stored at ﹣20 ℃ within 50 days (Mean ± SD = 11.747 ± 2.951 ng/g, F = 1.966, n = 81, P > 0.05). However, the cortisol concentrations of the fecal samples stored at 4 ℃ or 20 ℃ showed a significant fluctuation (4 ℃: Mean ± SD = 15.951 ± 6.766 ng/g, F = 23.643, P < 0.05; 20 ℃: Mean ± SD = 11.042 ± 6.094 ng/g, F = 35.126, P < 0.05). The cortisol concentration of the samples stored at 4 ℃ or 20 ℃ rose substantially after the first 24 h, and then declined after several days (Fig. 1). The results indicate that freezing at ﹣20 ℃ is a simple and reliable storage method for fecal cortisol in Prewalski′s gazelle. Meanwhile, because non-fresh fecal samples exposed in the field over 24 h may cause erroneous results, researchers should consider such potential effects when collecting fecal samples.