Faecal glucocorticoid (GC) and triiodothyronine (T3) metabolites and their interactions are increasingly used to monitor perceived stress and nutritional challenges in free-ranging animals. However, a number of extrinsic and intrinsic factors including hormone-inert dietary materials, inorganic matters etc. are known to affect reliable hormone metabolite quantifications. In this study, the impacts of inorganic matter (IOM) on faecal GC (fGCMs) and T3 (fT3Ms) metabolite measure were addressed in wild tiger (n = 193 from Terai Arc landscape, India) and captive lion (n = 120 from Sakkarbaug Zoological Garden, Gujarat, India) and possible corrective measures were evaluated. The wild tiger samples contained highly variable IOM content (9–98%, mostly with > 40% IOM) compared to captive Asiatic lion (17–57%, majority with < 40% IOM). Significant correlations were observed between IOM content and tiger fGCM (r = -0.46, p = 0.000), fT3M (r = -0.58, p = 0.000) and lion fT3M measures (r = -0.43, p = 0.003). Two corrective measures viz. removing samples with ≥ 80% IOM and subsequently expressing concentrations as per gram of organic dry matter (instead of total dry matter) reduced IOM influence on tiger fGCM, fT3M and lion fT3M, without affecting lion fGCM measures. The corrective measures changed the interpretations of fT3M data of field-collected tiger samples with no significant changes in fGCM (both tiger and lion) and fT3M (lion) data. As faecal IOM content is common in many wild species, the results emphasize the need to reduce IOM-driven hormone data variation for ecologically relevant interpretations towards species conservation.

粪便糖皮质激素 (GC) 和三碘甲状腺原氨酸 (T3) 代谢物及其相互作用越来越多地用于监测自由放养动物的感知压力和营养挑战。然而，已知许多外在和内在因素（包括激素惰性膳食材料、无机物等）会影响可靠的激素代谢物定量。在这项研究中，无机物 (IOM) 对粪便 GC (fGCMs) 和 T3 (fT3Ms) 代谢物测量的影响在野生老虎（来自印度 Terai Arc 景观的 n = 193）和圈养狮子（来自 Sakkarbaug 的 n = 120动物园，古吉拉特邦，印度）和可能的纠正措施进行了评估。与圈养亚洲狮（17-57%，大多数 IOM < 40%）相比，野生虎样本的 IOM 含量变化很大（9-98%，大部分 IOM > 40%）。在 IOM 含量和老虎 fGCM (r = -0.46, p = 0.000)、fT3M (r = -0.58, p = 0.000) 和狮子 fT3M 测量 (r = -0.43, p = 0.003) 之间观察到显着相关性。两个纠正措施，即。去除 IOM ≥ 80% 的样品，随后以每克有机干物质（而不是总干物质）表示浓度，减少了 IOM 对老虎 fGCM、fT3M 和狮子 fT3M 的影响，而不影响狮子 fGCM 措施。纠正措施改变了对野外采集的老虎样本的 fT3M 数据的解释，而 fGCM（老虎和狮子）和 fT3M（狮子）数据没有显着变化。由于粪便 IOM 含量在许多野生物种中很常见，因此结果强调需要减少 IOM 驱动的激素数据变化，以便对物种保护进行生态相关解释。