Selection for nutrients by red deer hinds feeding on a mixed forest edge |
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Authors: | Hélène Verheyden-Tixier Pierre-Cyril Renaud Nicolas Morellet Jacqueline Jamot Jean-Michel Besle Bertrand Dumont |
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Institution: | (1) INRA, Comportement et Ecologie de la Faune Sauvage, BP 27, 31326 Castanet-Tolosan, France;(2) INRA, Unité de Recherches sur les Herbivores, Theix, 63122 Saint-Genès-Champanelle, France |
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Abstract: | We studied the nutritional behaviour of hinds foraging on a mixed-forest edge by direct observation of their choices at each
season and by measuring nutrient concentration in the plants. We compared nutrient concentrations in the observed diets with
those in the total available vegetation, and with those of 1,000 randomly simulated diets in which we included only those
plants that were actually eaten by the animal. Whether the available or the consumed feeds were used as the basis for comparisons
had important consequences due to the presence of conifers and ferns, which were high in soluble sugars but were never eaten
by the animals (potentially due to their toxicity). The selected diets were lower in sugars than the total available vegetation
in summer, but were actually higher in sugars than the random diets generated from consumed forage species only. Hind diets
contained more soluble sugars but not more protein than simulated diets in all seasons. Contrary to our prediction, anti-nutritional
compounds (ADL and tannins) were avoided only in winter. Compared to simulated diets, hinds consumed more tannins in spring
and summer and more ADL in summer and autumn. We suggest that this was a consequence of selection for soluble sugars, because
the preferred plant species, which had high soluble sugar concentrations, also contained a large proportion of the anti-nutritional
compounds eaten. In winter, the grass-dominated diets contained more fibre (NDF) and less ADL than the simulated diets, indicating
that hinds orient their feeding towards digestible fibres. The switch from a browser to a grazer diet was related to a change
in the availability of the nutrients, mainly soluble sugars. In our study, grasses contained more soluble sugars and proteins
than deciduous browse during winter. This calls into question the dichotomy usually assumed in the literature between grass
and browse in terms of nutrient content.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. |
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Keywords: | Cervus elaphus Fibre Protein Sugar Tannin |
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