QUANTITATIVE MEASUREMENT OF FIBER FRACTIONS OF COOL-SEASON AND WARM-SEASON GRASS HERBAGE USING CELL-WALL-DEGRADING ENZYMES

Quantitative in vitro methods using commercial cellulase (GEL), pectin ase (PECT), and hemicellulase (HCEL) preparations were developed to si mplify prediction of digestibility of cool- and warm-season forage gra sses. Samples of orchardgrass (Dactylis glomerata L. var. Pennlate), t all fescue (Festuca arundinacea Schreb. var. KY 31) (cool-season grass es), big bluestem (Andropogon gerardi Vitman var. NY 1145), and switch grass (Panicum virgatum L. var. KY 1625) (warm-season grasses) were ta ken at advancing stages of maturity. Isolated cell-wall material (CWM) was prepared by repetitively extracting lyophilized, ground tissue wi th aqueous and organic solvents. Relative solubilities of CWM digested individually with GEL, HCEL, or PECT were 100:30:40, respectively. Wh en enzyme preparations were used sequentially, the influence of GEL, H CEL, and PECT on CWM solubility depended on the order in which the enz yme preparations occurred in the sequence. The fraction of CWM solubil ized with CEL was similar to that obtained when CWM was digested with GEL, HCEL, and PECT simultaneously. Solubilities of cell-wall material in unfractionated tissues digested with CEL were comparable to those of corresponding CWM digested with GEL; thus, the laborious steps requ ired for isolation of cell-wall, material can be avoided.