Diversity in the chemical composition and digestibility of leaves from fifty woody species in temperate areas

In temperate regions, tree leaves could be a source of energy, protein, vitamins and minerals for ruminants. Our objective was to study the diversity in chemical composition and digestibility of leaves on a panel of native woody species or potentially adapted to temperate regions. The leaves of 28 trees, 14 shrubs and 8 liana species were collected during summer across locations in France. Shoots of 8 herbaceous species were also collected for comparison. Fodder samples were analysed for in vitro digestibility (IVDMD), dry matter content and concentrations in crude protein (CP), neutral and acid detergent fiber, acid detergent lignin, ash, condensed tannins (CT), and macro and micro minerals. All these variables, expressed on DM basis, varied widely according to species (P < 0.001) and life form (P < 0.001). Overall DM content (mean = 375 g kg−1 fresh matter), IVDMD (66%), concentrations in CP (145 g kg−1) and Ca (18 g kg−1) of woody species leaves were similar to the range seen in traditional herbaceous forage. Leaves CP concentration of 44% of the woody species was higher than 140 g kg−1 and 34% of woody species showed leaves IVDMD greater than 70%. Leaves CT concentration varied from 0.1 to 190 g kg−1 according to species. Average CT concentration of lianas (52 g kg−1) was significantly higher (p < 0.001) than trees (28 g kg−1) and shrubs (25 g kg−1). Three clusters of species were identified by the hierarchical clustering on principal components. The species belonging to the same phylogenetic family were often gathered in the same cluster and there was no evidence of an effect of the life form on the classification of species. Species such as Morus alba, Sambucus nigra, Ficus carica, Prunus spinosa or Passiflora edulis showed high values in CP, Ash, Ca, K, Mg, IVDMD and P concentrations and could be used as dietary supplements. This study is one of the first to report in details chemical composition and IVDMD of large number of trees, shrubs and liana species.