Varietal differences in rumen degradation of barley, wheat and hard wheat straws

The rumen dry-matter degradation of straw from nine varieties of barley, nine varieties of wheat and seven varieties of hard wheat was studied to provide further information on varietal differences and their relationships with agronomic characteristics. In all the cereals there were significant differences in in situ dry-matter disappearance between varieties. The range of differences was lower in hard wheat varieties compared with the other cereals. There were no significant correlations between straw degradability and plant height, days from sowing to heading and grain production and quality. Lignin concentration was significantly correlated to straw degradability (r = −0·937 in barley, −0·675 in wheat and −0·987 in hard wheat). Leaf had lower concentrations of lignin and higher degradability than stem in barley and wheat but the two fractions were similar in hard wheat straws. The differences in degradation between the most and the least degradable straw varieties of each cereal species were mainly due to differences in degradability of both the fractions whereas the role of leaf and stem proportions was of minor importance.