Ojala Eeva A, Kurkilahti Mika, Hovland Anne Lene, Palme Rupert, Mononen Jaakko
Faculty of Veterinary Medicine, University of Helsinki, 00790 Helsinki, Finland.
Natural Resources Institute Finland (Luke), Itäinen Pitkäkatu 4 A, 20520 Turku, Finland.
Animals (Basel). 2021 Sep 7;11(9):2631. doi: 10.3390/ani11092631.
Welfare studies of blue foxes would benefit from a measurement of faecal cortisol metabolites (FCMs) as a non-invasive, physiological stress parameter reflecting hypothalamus-pituitary-adrenal (HPA) axis activity. Before implementation, a species-specific validation of such a method is required. Therefore, we conducted a physiological validation of an enzyme immunoassay (EIA) to measure FCMs in blue foxes. Twenty individuals (nine males and eleven females) were injected with synthetic adrenocorticotrophic hormone (ACTH) and faecal samples were collected every third h for two days. The FCM baseline levels were assessed based on the first sampling day (control period, 144 samples), followed by the ACTH injection and the second day of sampling (treatment period, 122 samples). FCMs were analysed with a 5α-pregnane-3ß,11ß,21-triol-20-one EIA. We compared the estimated mean FCM concentrations of the treatment samples to the baseline average. All samples for the two periods were collected at the same time of the day, which enabled to test the data also with an hourly pairwise comparison. With the two statistical approaches, we tested whether a possible diurnal fluctuation in the FCM concentrations affected the interpretation of the results. Compared to the baseline levels, both approaches showed 2.4-3.2 times higher concentrations on time points sampled 8-14 h after the ACTH injection ( < 0.05). The estimated FCM concentrations also fluctuated slightly within the control period ( < 0.01). Inter-individual variations in FCM levels were marked, which highlights the importance of having a sufficient number of animals in experiments utilising FCMs. The sampling intervals of 3 h enabled forming of informative FCM curves. Taken together, this study proves that FCM analysis with a 5α-pregnane-3ß,11ß,21-triol-20-one EIA is a valid measurement of adrenocortical activity in the farmed blue foxes. Therefore, it can be utilised as a non-invasive stress indicator in future animal welfare studies of the species.
对蓝狐进行福利研究时，若能测量粪便皮质醇代谢物（FCMs），将大有益处。FCMs作为一种非侵入性的生理应激参数，可反映下丘脑 - 垂体 - 肾上腺（HPA）轴的活动。在应用该方法之前，需要对其进行特定物种的验证。因此，我们对一种用于测量蓝狐FCMs的酶免疫测定法（EIA）进行了生理验证。选取20只个体（9只雄性和11只雌性），给它们注射合成促肾上腺皮质激素（ACTH），并在两天内每3小时采集一次粪便样本。基于第一天的采样（对照期，144个样本）评估FCM基线水平，随后进行ACTH注射并在第二天采样（治疗期，122个样本）。使用5α - 孕烷 - 3β，11β，21 - 三醇 - 20 - 酮EIA分析FCMs。我们将治疗样本的估计平均FCM浓度与基线平均值进行比较。两个时期的所有样本均在一天中的同一时间采集，这使得我们也能够通过每小时的成对比较来检验数据。通过这两种统计方法，我们检验了FCM浓度可能存在的昼夜波动是否会影响结果的解释。与基线水平相比，两种方法均显示在ACTH注射后8 - 14小时采集的时间点上，浓度高出2.4 - 3.2倍（<0.05）。在对照期内，估计的FCM浓度也有轻微波动（<0.01）。FCM水平的个体间差异显著，这突出了在利用FCMs的实验中要有足够数量动物的重要性。3小时的采样间隔能够形成信息丰富的FCM曲线。综上所述，本研究证明使用5α - 孕烷 - 3β，11β，21 - 三醇 - 20 - 酮EIA进行FCM分析是养殖蓝狐肾上腺皮质活动的有效测量方法。因此，在未来该物种的动物福利研究中，它可作为一种非侵入性应激指标加以利用。
