Cell wall composition and digestibility in five species of Brachiaria
Keywords:Congo grass, Fibre composition, Fibre digestibility, Forage quality, Cell wall monosaccharides
AbstractFive species of Brachiaria with varying numbers of accessions were screened to identify those of higher nutritive value. Significant differences were observed between species, as well as between accessions within species, in cell wall constituents and digestibility. Brachiaria ruziziensis had the lowest (P < 0.05) neutral detergent fibre, acid detergent fibre, cellulose and hemicellulose concentrations of all species studied, in both leaf and stem fractions. Stems were higher (P < 0.05) in cellulose and lignin, and equal to or higher than leaves in hemicellulose for each species studied. Species differences were more evident in leaf than in stem compositions, indicating a less variable fibre composition in the stem fraction. Brachiaria ruziziensis had the highest (P < 0.5) digestibility of all species despite having higher (P < 0.05) leaf lignin concentrations. Cell wall digestibility of stems of all species was 150-200 g kg-1 lower (P < 0.05) than that of leaves. Considerable variation existed in both cell wall composition and digestibility among accessions, indicating that it should be possible to select the higher-quality genotypes of each species as initial materials for further improvement by breeding.