EFFECT OF DIRECT-FED FIBROLYTIC ENZYMES ON THE DIGESTIVE CHARACTERISTICS OF A FORAGE-BASED DIET FED TO BEEF STEERS

A study was conducted to examine the method of delivery of a solution containing cellulases and xylanases on the digestion of a forage-based diet. Five ruminally cannulated beef steers (536 kg BW) were randomly assigned to a control(CON) or one of four enzyme treatments in a 5 x 5 Latin square experiment. Steers were fed a 70:30 (DM basis) grass ha y:barley diet. Enzyme-treated rations contained a solution of fibrolyt ic enzymes at the rate of 1.65 mL/kg of forage DM. Enzyme application treatments were 1) enzyme to forage 24 h before feeding (F-24), 2) enz yme to forage 0 h before feeding (F-0), 3) enzyme to barley 0 h before feeding (B-0), and 4) enzyme infused ruminally 2 h after feeding(RI). Dry matter and NDF intakes were not different (P >.10) across treatme nts. Ruminal pH was lower and total VFA concentration at 16 h after-fe eding was greater (P < .10) for steers fed enzyme treatments compared with CON. Rate of NDF disappearance was greater (P < .05) for enzyme-t reated than for untreated grass substrate. Ruminal infusion of enzymes compared with F-24 and F-0 produced lower disappearance of DM at 8 an d 32 h (P <.10), NDF at 32 h (P <.10), and DM and NDF at 96 h (P <.05) . Rate of DM disappearance of enzyme-treated grass hay was greater (P <.10) for steers fed B-O than for those fed F-24 and F-0 and for CON t han for F-24 and F-0. Total tract digestibility of Dill, NDF, and ADF was greater (P <.10) for F-24 and F-0 than for CON. Forage transit tim e was shorter(P <.10) for B-O than for F-24 and F-0; however, all othe r contrasts for particulate passage did not differ (P >.10). Results f rom this study indicate that direct application of enzymes to forages is capable of improving forage digestion.