Abstract：
Dealing with potential stress in species that have high husbandry requirements, such as elephants, is a challenge for zoos. The objective of the present study was to determine whether positive reinforcement training (PRT) and exposure to a novel object (NOV) for enrichment induced a salivary cortisol response indicative of activation of the hypothalamic-pituitary-adrenal (HPA) axis and which factors determine individual variation in this regard in captive African elephants. We repeatedly sampled the saliva of ten animals (three zoos) for the analysis of cortisol (SACort) before and up to 60 min (in 10-15 min intervals) after the onset of PRT (three repeats) or NOV (nine repeats), which lasted 10 min. There was considerable individual variation in SACort in response to PRT or NOV. Using mixed models, we were able to control these and to reveal that PRT was associated with high SACort before and relatively low SACort after PRT, while NOV induced a moderate SACort increase. The individual differences in SACort were related to age and sex (NOV), while the effects of zoo, handling method (free vs. protected contact) and reproductive and social status were variable. We conclude that positive affective states, such as anticipation or arousal, should be taken into account when interpreting the differences in the SACort responses between PRT and NOV. In addition, understanding the individuality of stress will support management decisions aimed at promoting captive elephant welfare.
摘要：
应对具有高饲养要求的物种的潜在压力，比如大象，对动物园来说是一个挑战。本研究的目的是确定积极的强化训练（PRT）和暴露于新物体（NOV）进行富集是否会引起唾液皮质醇反应，表明下丘脑-垂体-肾上腺（HPA）轴激活，以及哪些因素决定圈养非洲象在这方面的个体差异。在PRT（三次重复）或NOV（九次重复）开始之前和之后60分钟（间隔10-15分钟），我们反复取样十只动物（三个动物园）的唾液以分析皮质醇（SACort），持续了10分钟。SACort对PRT或NOV的反应存在相当大的个体差异。使用混合模型，我们能够控制这些，并揭示PRT与PRT之前的高SACort和PRT之后的相对低SACort相关，而NOV诱导了适度的SACort增加。SACort的个体差异与年龄和性别（NOV）有关，而动物园的影响，处理方法(免费与受保护的接触)和生殖和社会地位是可变的。我们得出的结论是，积极的情感状态，如期待或唤醒，在解释PRT和NOV之间的SACort响应差异时，应予以考虑。此外,了解压力的个性将支持旨在促进圈养大象福利的管理决策。
