Cell‐wall constituents of some grass species and varieties

Structural carbohydrates and lignin were determined in two varieties each of perennial ryegrass, cocksfoot and timothy during first growth. Structural carbohydrates were extracted with N‐sulphuric acid and with 72% sulphuric acid and partitioned by paper chromatography. The content of structural constituents increased and in vitro digestibility decreased as the grasses matured. When compared at the same growth stage, perennial ryegrass varieties were higher in digestibility and lower in lignin than the other grasses. When compared at the same level of dry matter digestibility cocksfoot varieties were lower in structural carbohydrates but higher in lignin than other grasses. Correlations between digestibility and the content of structural constituents including fibre were highly significant. The results are discussed with reference to the effect of varietal variation in structural constituents on digestibility and voluntary intake.