EFFECT OF HYDROGEN PEROXIDE-DEPENDENT ENZYME-SYSTEMS ON THE IN-VITRO DIGESTIBILITY OF UNTREATED AND AMMONIA-TREATED BARLEY STRAWS

A series of small-scale in vitro experiments was conducted to evaluate the effectiveness of various hydrogen peroxide (H2O2)-dependent enzyme systems, peroxidase and glucose oxidase, in improving the nutritive value of ammonia-treated and untreated barley straw. H2O2 and peroxidase increased (P < 0.001) digestibilities when used individually, but their combined use did not influence digestibility significantly (P > 0.05). The effect of H2O2 alone was greater than that of peroxidase alone. The combination of glucose and glucose oxidase to generate H2O2 produced a small but non-significant (P > 0.05) increase in the digestibility of straw. The combination of glucose oxidase and peroxidase was ineffective in improving digestibility of straw. The digestibility values of ammonia-treated barley straw were always greater (P < 0.001) than those of untreated straw but none of the treatments showed any interaction with ammonia treatment. It is suggested that H2O2 treatment improves the digestibility of straw.