Acetyl and phenolic acid substituents in timothy of different maturity and after digestion with rumen microorganisms or a commercial cellulase

Timothy grown in northern Sweden was harvested at varying maturity. Residues were prepared by extraction with ethanol or incubation in vitro, using rumen liquor or a commercial cellulase. The content of acetyl and phenolic (p-coumaric- and ferulic acid) substituents increased with maturity in all residues. Incubation with rumen liquor caused removal of a higher proportion of the substituents than the cellulase treatment. It was notable that ferulic acid was removed to a much greater extent than p-coumaric acid substituents. Acetyl and p-coumaric acid substituents, assumed to be linked mainly to the xylans, were proportionally less digestible in rumen liquor than xylose.