The effect of pepsin pretreatment of herbage on the prediction of dry matter digestibility from solubility in fungal cellulase solutions

Cellulase preparations from different fungi differed markedly in their ability to solubilise herbage and cellulose; T. viride cellulase was the most active, solubilising 70% of cellulose paper in 24 h. The correlation of cellulase solubility with the in vivo and in vitro dry matter digestibility of grasses, and with the in vitro digestibility of legumes was markedly improved by pretreatment of the herbage with acid pepsin. Using the two stage technique, closely similar regression lines were obtained for predicting the in vitro digestibility of both grasses and legumes. Use of the pepsin treatment also enabled a less active Basidiomycete cellulase to be used with results very similar to those obtained with the T. viride enzyme. The technique is proposed as a more rapid, convenient and precise method of predicting digestibility than the usual in vitro procedure.