Clauss Marcus, Lason Karin, Gehrke Janin, Lechner-Doll Matthias, Fickel Jörns, Grune Tilman, Jürgen Streich W
Institute of Animal Physiology, Physiological Chemistry and Animal Nutrition, Veterinaerstr. 13, Munich 80539, Germany .
Comp Biochem Physiol B Biochem Mol Biol. 2003 Oct;136(2):369-82. doi: 10.1016/s1096-4959(03)00244-6.
Browsing ruminants have been shown to tolerate a certain amount of tannins in their natural diet, and preference trials with captive roe deer (Capreolus capreolus) have suggested an active selection for a low dose of hydrolysable tannins. In this study, we investigated the preference patterns for tannic acid, a source of hydrolysable tannins, and quebracho, a source of condensed tannins, in a series of preference trials with captive roe deer over time, using a pelleted feed that differed only in the respective tannin content. Additionally, two groups of four hand-raised roe deer fawns were fed either a control or a 3% tannic-acid containing diet and physiological parameters were compared after 7.5 months. There were large differences in preference patterns between the individual roe deer groups; quebracho was mostly avoided, whereas tannic acid was actively included in the diet in differing, low proportions. However, one group consistently preferred the quebracho diet over both the control or the tannic acid diet. For the tannic acid, the preference pattern often revealed an initial period of high preference, followed by a stable period of a moderate preference. The fawns on the tannic acid diet had a lower pellet intake and a higher relative mass gain than the fawns on the control diet; differences in salivary tannin-binding capacity and in blood antioxidant status were below significance. These results are the first indications of potential benefits of a low-dose tannin diet, which need further confirmation. The results of the preference trials demonstrate that the time pattern of tannin intake is not constant, and pose the question about the validity of short-term preference trials in general.
研究表明，放牧反刍动物在其自然饮食中能够耐受一定量的单宁，对圈养狍（Capreolus capreolus）进行的偏好试验表明，它们会主动选择低剂量的可水解单宁。在本研究中，我们在一系列针对圈养狍的偏好试验中，随着时间推移，使用仅单宁含量不同的颗粒饲料，研究了可水解单宁来源单宁酸和缩合单宁来源白坚木皮栲的偏好模式。此外，将两组各四只人工饲养的狍幼崽分别喂食对照饲料或含3%单宁酸的饲料，并在7.5个月后比较生理参数。不同狍群之间的偏好模式存在很大差异；白坚木皮栲大多被拒食，而单宁酸则以不同的低比例被主动纳入饮食。然而，有一组始终对白坚木皮栲饲料的偏好高于对照饲料或单宁酸饲料。对于单宁酸，偏好模式通常显示出一个最初的高偏好期，随后是一个稳定的中等偏好期。食用单宁酸饲料的幼崽比食用对照饲料的幼崽采食量低，但相对体重增加更高；唾液单宁结合能力和血液抗氧化状态的差异不显著。这些结果首次表明低剂量单宁饮食可能存在益处，但需要进一步证实。偏好试验结果表明，单宁摄入的时间模式并非恒定不变，总体上也引发了关于短期偏好试验有效性的问题。
