p‐Coumaric and ferulic acid components of cell walls of ryegrass and their relationships with lignin and digestibility

Abstract

Abstract Cell walls, isolated from vegetative Italian ryegrass, pre‐ and post‐flowering perennial ryegrass and the faeces of sheep fed the perennial ryegrass, were treated with alkali and the liberated p ‐coumaric acid (PCA), ferulic acid (FA) and vanillin estimated. A higher yield of the two acids was obtained from the Italian than from the perennial ryegrass. Oxidation of the cell‐wall residues indicated the presence of the 1‐phenylpropene structural unit in the lignin cores. There was a highly significant correlation between the digestibility of the cell walls from perennial ryegrass and the FA/PCA ratio. The recovery of PCA (24 to 59 %) from the faecal cell walls was much higher than that of FA (5 to 21 %). For each acid this recovery was lower in the pre‐flowering herbage.