An in vitro assay was carried out to evaluate the effects of exogenous fibrolytic enzymes (1, 2, 3 and 4 g/kg DM) powder preparation containing xylanase and cellulase from Aspergillus niger and Trichoderma viride on DM, NDF and ADF degradation of alfalfa hay, corn silage, corn stover, elephant grass, Guinea grass and oat straw. Kinetics data of in vitro degradations were analyzed. The potentially degradable fraction and degradation rate of NDF and ADF of alfalfa increased quadratically (P<0.05)

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... as the inclusion level of enzyme increased up to 3 g. The others forages were not affected by the enzyme. An in sacco trail was performed using four Holstein steers fitted with ruminal cannulas to evaluate the effects of the exogenous fibrolytic enzymes (3 g/kg DM) on DM, NDF and ADF degradation of alfalfa hay and corn stover. Kinetics data were also analyzed. The potentially degradable fraction degradation of NDF (62.0 vs 65.7%) and ADF (52.8 vs 56.9%), of alfalfa hay were increased (P<0.05) by the exogenous fibrolytic enzymes, but no differences were found for corn stover. These results suggest that the enzymes increased in vitro and in sacco fibre degradation only for alfalfa hay.