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 °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 °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 °C.

Keywords: Fibrolytic enzyme, in vitro gas production, metabolizable energy, rice straw

Full Text: PDF