EFFECTIVE OF ENZYME PREPARATIONS ON IN-SITU AND IN-VITRO DEGRADATION AND IN-VIVO DIGESTIVE CHARACTERISTICS OF MATURE COOL-SEASON GRASS FORAGE IN BEEF STEERS

In situ and in vitro studies with a 3 x 2 x 5 factorial arrangement of treatments with an added untreated control evaluated three enzyme pre parations, two levels of enzyme, and five moisture conditions of grass forage. Enzyme preparations predominantly contained cellulase and xyl anase and will be designated as enzyme 1 (E1), enzyme 2 (E2), and a 50 :50 combination of E1 and E2 (E1E2). The five moisture conditions incl uded fresh, wilted, dried and rehydrated to fresh, dried and rehydrate d to wilt, and dried grass. Addition of the high level of E1E2 to drie d grass improved (P < .05) in vitro DM (43.5 vs 38.7%) and NDF (31.1 v s 26.0%) disappearance (48 h incubation) compared with the control tre atment. Also, IVDMD was greater (P < .05) for the low level of E1 appl ied to wilted grass compared with the control. No other enzyme applica tion improved in situ or in vitro disappearance of substrate over the control. In vivo responses of enzyme treatments found most likely to b e effective from degradability studies were measured using four rumina lly cannulated steers in a 4 x 4 Latin square experiment. Treatments e xamined were E1 applied to fresh forage, then dried; E1 applied to wil ted forage, then dried; E1E2 applied to dry forage immediately before feeding (E-dry), and untreated forage (control). All forage treatments were harvested as dry hay. Total diet and hay DM intakes were greater (P < .05) for the E-dry than for the control diet. Rate of in situ ND F disappearance and total tract DM and NDF digestibility were greater (P < .05) for the E-dry than for the other treatments. Ruminal fluid a mmonia N concentration, total VFA concentration, and pH were not alter ed (P > .10) by dietary treatment. Ruminal particulate passage rate wa s greater (P < .05) and ruminal retention time was shorter (P < .05) f or the E-dry than for the control treatment. Data from this study sugg est that addition of fibrolytic enzymes to grass hay before feeding ha s the potential to enhance intake and digestion.