Produção, caracterização e avaliação de enzimas fibrolíticas na digestibilidade da forragem de milho

Abstract

The objectives of this research were to produce and characterize an enzyme complex (EC), using the fungus Humicola grisea, and evaluate its effect on true digestibility of forage maize dry matter. We observed that the fungus produced cellulase, β-glucosidase and xylanase enzymes. The cellulase and xylanase activities were high at the temperature of 50° C. The optimum temperature of β-glucosidase was between 50 and 60° C. The optimum pH of cellulase and xylanase enzyme was 6.0. As for β- glucosidase, the enzyme showed higher activity at pH 6.5. Cellulase remained stable for 60 minutes at 39° C. Xylanase and β-glucosidase maintained 99.2 and 88.2% of their activity at 50° C for 240 minutes, respectively. The treatments were as follows: control (10 mL of sterile water), level 1 (2.5 mL EC), level 2 (5.0 mL EC) and level 3 (10 mL EC). In the digestibility experiment, there was interaction between enzyme levels and time of incubation in the rumen. The addition of 10 mL of the fibrolytic enzymes improved the digestibility at 10.58; 12.52; 9.05 and 6.81% compared to control for 12; 24; 48 and 96 hours of incubation, respectively. The fungus Humicola grisea is an enzyme producer that is important in ruminant feed.