Abstract
Ferulate ethers and lignin in straw of barley (Hordeum vulgate L.) cultivars and stalk of sorghum (Sorghum bicolor Moench) with different maturity were determined to relate to dry matter degradability (DMD) and proportion of arabinose residues carrying alkali-labile substituents at position O-5. The susceptibility of botanical fractions and fractionated specific tissue cell walls of barley straw to degradation by rumen microorganisms and enzymes was also related to ferulate ethers and lignin. The content of ferulate ethers in barley straw and sorghum stalk was inversely related to DMD and positively to the proportion of alkali-labile substitution of 0-5 arabinose residues. The phenolic contents of whole straw were largely determined by phenolic contents of the stem fraction. The phenolic components recognizable in the stem fraction were also more influenced by the composition of the fibrous cell walls than that of the parenchyma cell walls. The DMD of such botanical fractions was also mostly responsible to the contents of ferulate ethers and lignin, although the susceptibility of specific cell was unclear.
