FIBER AND SOLUBLE PHENOLIC MONOMER COMPOSITION OF MORPHOLOGICAL COMPONENTS OF SORGHUM STOVER

Studies were conducted to characterise the fibre and phenolic composition, and measure digestibility of diverse sorghum [Sorghum bicolor (L) Moench] genotypes, including brown-midrib (bmr6) and normal genotypes separated into leaf blade, leaf sheath and stem. Other than lignin, fibre composition varied little among genotypes. In contrast to most forage crops, leaf sheath was consistently higher than leaf blade or stem in neutral detergent fibre, acid detergent fibre and cellulose and lower in in-vitro dry matter digestibility. Of the phenolic acid compounds investigated, p-coumaric acid (PCA) was observed in the largest quantities. Alkali-labile PCA was higher in stem than leaf tissues of all genotypes. Alkali-labile PCA was lower in the 'Redlan' bmr6 genotype than in the 'Redlan' normal genotype. Solubility of PCA and ferulic acid in neutral detergent was generally < 30%.