Effects of Supplementing a Fibrolytic Feed Enzyme on the Growth Performance and Carcass Characteristics of Beef Steers1

The objective of this study was to determine the growth performance of growing and finishing beef steers when fed with a fibrolytic feed enzyme (FFE) in a completely randomized design. This experiment was conducted during growing and finishing periods using 60 group-penned Angus crossbred steers randomly assigned to treatments: control (no enzyme), low enzyme, and high enzyme. For the enzyme treatments, the FFE was added to the control diet at a dose of 1 or 2 g enzyme/kg DM TMR for the low-enzyme or high-enzyme treatment, respectively. Supplementing the growing diet with FFE did not affect DMI, regardless of dose rate. Body weight gain was not affected by FFE supplementation. Supplementation with FFE did not affect ADG and G:F. The overall growth performance during the finishing period was not influenced by the FFE, as was seen in the growing period. However, supplementation with FFE reduced 12th-rib fat thickness (P < 0.01) and tended to decrease the marbling score (P = 0.14) across both enzyme doses. Supplementing the beef growing and finishing diets with FFE at 1 and 2 g/kg DM TMR did not affect growth performance and had minor effects on the carcass characteristics of beef steers.