title: Factors Affecting Leaf Selection by Foregut-fermenting Proboscis Monkeys: New Insight from in vitro Digestibility and Toughness of Leaves.
abstract: 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.
authors.affiliation: 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.|Japan Monkey Centre, 26 Kanrin, Inuyama, Aichi 484-0081, Japan.|Institute for Tropical Biology and Conservation, Universiti Malaysia Sabah, Jalan UMS, 88400 Kota Kinabalu, Sabah, Malaysia.
authors.forename: Ikki
authors.initials: I
authors.lastname: Matsuda
authors.affiliation: Clinic for Zoo Animals, Exotic Pets and Wildlife, Vetsuisse Faculty, University of Zurich, Winterthurerstrasse 260, 8057 Zurich, Switzerland.
authors.forename: Marcus
authors.initials: M
authors.lastname: Clauss
authors.affiliation: Sabah Wildlife Department, Sabah, Malaysia, 5th Floor, B Block, Wisma MUIS, 88100 Kota Kinabalu, Sabah, Malaysia.
authors.forename: Augustine
authors.initials: A
authors.lastname: Tuuga
authors.affiliation: Forest Research Center, P.O. Box 1407, 90715 Sandakan Sabah, Malaysia.
authors.forename: John
authors.initials: J
authors.lastname: Sugau
authors.affiliation: Primate Research Institute, Kyoto University, Kanrin, Inuyama, Aichi 484-8506, Japan.
authors.forename: Goro
authors.initials: G
authors.lastname: Hanya
authors.affiliation: Primate Research Institute, Kyoto University, Kanrin, Inuyama, Aichi 484-8506, Japan.
authors.forename: Takakazu
authors.initials: T
authors.lastname: Yumoto
authors.affiliation: Institute for Tropical Biology and Conservation, Universiti Malaysia Sabah, Jalan UMS, 88400 Kota Kinabalu, Sabah, Malaysia.
authors.forename: Henry
authors.initials: H
authors.lastname: Bernard
authors.affiliation: Department of Animal Sciences, University of Göttingen, Kellnerweg 6, 37077 Göttingen, Germany.
authors.forename: Jürgen
authors.initials: J
authors.lastname: Hummel
mesh_terms: D000818:Animals; D004063:Digestion; D005260:Female; D005518:Food Preferences; D000882:Haplorhini / Q000502:physiology*; D060434:Herbivory; D008297:Male; D018515:Plant Leaves / Q000737:chemistry*