Chubu University Academy of Emerging Sciences, 1200, Matsumoto-cho, Kasugai-shi, Aichi 487-8501, Japan.
Wildlife Research Center of Kyoto University, 2-24 Tanaka-Sekiden-cho, Sakyo, Kyoto 606-8203, Japan.
Sci Rep. 2017 Feb 17;7:42774. doi: 10.1038/srep42774.
Free-living animals must make dietary choices in terms of chemical and physical properties, depending on their digestive physiology and availability of food resources. Here we comprehensively evaluated the dietary choices of proboscis monkeys (Nasalis larvatus) consuming young leaves. We analysed the data for leaf toughness and digestibility measured by an in vitro gas production method, in addition to previously reported data on nutrient composition. Leaf toughness, in general, negatively correlated with the crude protein content, one of the most important nutritional factors affecting food selection by leaf-eating primates. This result suggests that leaf toughness assessed by oral sensation might be a proximate cue for its protein content. We confirmed the importance of the leaf chemical properties in terms of preference shown by N. larvatus; leaves with high protein content and low neutral detergent fibre levels were preferred to those of the common plant species. We also found that these preferred leaves were less tough and more digestible than the alternatives. Our in vitro results also suggested that N. larvatus were little affected by secondary plant compounds. However, the spatial distribution pattern of plant species was the strongest factor explaining the selection of the preferred leaf species.
自由生活的动物必须根据其消化生理学和食物资源的可利用性，在化学和物理性质方面做出饮食选择。在这里，我们全面评估了食用嫩叶的长鼻猴（Nasalis larvatus）的饮食选择。我们分析了通过体外产气法测量的叶片韧性和消化率的数据，以及之前关于营养成分的报告数据。一般来说，叶片韧性与粗蛋白含量呈负相关，粗蛋白含量是影响食叶灵长类动物食物选择的最重要营养因素之一。这一结果表明，通过口腔感觉评估的叶片韧性可能是其蛋白质含量的一个近因线索。我们通过长鼻猴的偏好证实了叶片化学性质的重要性；具有高蛋白含量和低中性洗涤剂纤维水平的叶片比常见植物物种的叶片更受欢迎。我们还发现，这些首选叶片比其他叶片更柔软，更易消化。我们的体外结果还表明，长鼻猴受次生植物化合物的影响较小。然而，植物物种的空间分布模式是解释首选叶片物种选择的最强因素。
