The present study assessed the diurnal variation in salivary cortisol in captive African elephants during routine management (baseline) and in relation to a potential stressor (translocation) to evaluate to what extent acute stress may affect diurnal cortisol patterns. Under baseline conditions, we collected morning and afternoon saliva samples of 10 animals (three zoos) on different days in two study periods (n = 3-10 per animal, daytime and period). Under stress conditions, we sampled the transported cow (newcomer) and the two cows of the destination zoo before and after the transport in the morning and afternoon (n = 3-9 per animal, daytime and transport phase), as well as after the first introduction of the newcomer to the bull (n = 1 per animal). Cortisol was measured in unextracted samples by enzyme immunoassay. Under baseline conditions, we observed the expected diurnal variation with higher cortisol levels in the morning than in the afternoon. Under stress conditions, neither a significant difference between pre- and posttransport, nor between morning and afternoon levels was found. The percentage difference between morning and afternoon cortisol after the transport, however, was remarkably lower than before the transport in the newcomer potentially indicating a stress response to familiarization. Saliva samples taken immediately after the introduction of the newcomer to the bull revealed a marked cortisol increase. Our findings indicate that stressors may disturb the diurnal cortisol rhythm. Furthermore, provided that samples can be collected promptly, salivary cortisol is a useful minimally invasive measure of physiological stress in the African elephant.

中文翻译：

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在常规管理条件下和与易位事件相关的圈养非洲象（非洲象属）唾液皮质醇的昼夜变化

本研究评估了圈养非洲大象在日常管理（基线）期间唾液皮质醇的昼夜变化以及与潜在压力源（易位）的关系，以评估急性压力对昼夜皮质醇模式的影响程度。在基线条件下，我们在两个研究时期（每只动物、白天和时期 n = 3-10）的不同日期收集了 10 只动物（三个动物园）的上午和下午唾液样本。在应激条件下，我们在上午和下午的运输前后（n = 3-9 每只动物，白天和运输阶段）以及运输后对目的地动物园的两只奶牛（新来者）和两只奶牛进行采样。首次将新来者引入公牛（每只动物 n = 1）。通过酶免疫测定法测量未提取样品中的皮质醇。在基线条件下，我们观察到预期的昼夜变化，早上皮质醇水平高于下午。在压力条件下，运输前和运输后之间以及上午和下午的水平之间均未发现显着差异。然而，运输后早上和下午皮质醇之间的百分比差异显着低于新来者运输前的百分比，这可能表明对熟悉的压力反应。将新来者引入公牛后立即采集的唾液样本显示皮质醇显着增加。我们的研究结果表明，压力源可能会扰乱昼夜皮质醇节律。此外，如果可以及时收集样本，唾液皮质醇是一种有用的微创测量非洲象生理压力的方法。