Composition and enzymatic digestibility of Oregon grass straws

Samples of nine species or types of commercial grass seed straws grown in Oregon were analyzed and treated with anhydrous ammonia in the laboratory. Enzymatic digestibility of treated and untreated materials was determined using commercial cellulase and protease. The mean composition of all nine species/types (based on six each within-group replicates) was: crude protein, 5.4%; NDF, 72.2%; ADF, 43.6%; hemicellulose, 26.4%; cellulose, 34.8%; and lignin, 6.9%. Significant species/type compositional differences were found. From their composition, several of the grass straws appeared to have better nutritional value than most cereal straws. Enzymatic digestibility of all straws was improved by ammoniation (average increase, 62%). Enzymatic digestibility ranged from about 27–42% for untreated materials to 43–66% for NH₃-treated products.