The determination of in vitro gas production and metabolizable energy value of rice straw treated with exogenous fibrolytic enzymes

Abstract

This study was conducted to determine the effects of cellulase and xylanase treatments on in vitro 24-h gas production (GP), organic matter digestibility (OMD), and metabolizable energy (ME) values of rice straw (RS). Rice straws were treated with cellulase and xylanase at the levels of 0% (C1), 0.5% (RS+CEL0.5), 1% (RS+CEL1), 1.5% (RS+CEL1.5), and 2% (RS+ CEL2) and 0% (C2), 0.5% (RS+XYL0.5), 1% (RS+XYL1), 1.5% (RS+ XYL1.5), and 2% (RS+XYL2), respectively. Rice straws treated with each level of cellulase and xylanase were ensiled in 6 glass jars. For each level of cellulase and xylanase treatment, 3 glass jars were incubated at room temperature, while 3 glass jars were incubated at 40 +/- 0.2 degrees C in an incubator for 30 days. In vitro GP for 24 h, OMD, and ME values in RS+ CEL2 were higher (P < 0.05) than those of C1 and the other groups treated with cellulase, while significant increases (P < 0.05) for the same parameters were obtained from RS+ XYL1 incubated at 40 +/- 0.2 degrees C, RS+ XYL1.5, and RS+ XYL2 compared to C2, RS+ XYL0.5, and RS+ XYL1 incubated at room temperature. In conclusion, in vitro 24- h GP, OMD, and ME values were the highest (P < 0.05) in the groups treated with the highest level of cellulase and xylanase incubated at 40 +/- 0.2 degrees C.