digestibility include the structura

digestibility include the structural fiber fractions (neutral detergent fiber NDF, acid detergent fiber ADF, lignin), the mineral concentration and composition, as well as crude protein and phenolics concentration. Increases in the fiber fractions (especially lignin) and phenolics are generally thought to decrease the digestibility of plant materials, while increases in protein concentration are seen as positive (Traxler et al., 1998; Mould, 2003)