| Digestibility and performance trials were conducted to determine the nutritional significance of dietary fiber in barley at the intestinal level of pigs and the efficacy of supplementation of specific enzymes. The mobile nylon bag technique with dual-cannulation of the small intestine (MNBTDC) was used for determining apparent ileal and fecal digestibilities of dietary fiber in barley. The MNBTDC was not different (P {dollar}>{dollar} 0.10, r = 0.99) from the indicator method in determination of dry matter digestibility (DMD), digestible energy (DE), or crude protein and acid detergent fiber digestibilities. Cellulose and arabinoxylans (AX) from barley disappeared primarily in the large intestine (38.5 and 35.5% of total digestibility, respectively) while most {dollar}beta{dollar}-glucans (BG) disappeared during gastric predigestion in vitro (68.7%). Addition of {dollar}beta{dollar}-glucanase and a mixed-enzyme product to the diet improved feed efficiency (P = 0.029). Fecal DMD and DE were improved by addition of either {dollar}alpha{dollar}-glucanase or mixed-enzyme product to diets based on low quality barley (P {dollar}{dollar} 0.10). Addition of specific enzymes (cellulase, xylanase or {dollar}beta{dollar}-glucanase) improved ileal DMD and DE by an average of 5.6 and 10.7%, respectively, compared to 3.2 and 3.6% for fecal digestibilities. The greatest improvements in ileal DMD and DE were observed when cellulase was added, while {dollar}beta{dollar}-glucanase and xylanase additions had less effect. Overall, these results suggest that AX may be a more important antinutritional factor in barley for pigs than BG because of their relative indigestibility in the stomach and small intestine and/or their inhibitory activity against utilization of other nutrients. Furthermore, cellulase is the most useful enzyme to improve utilization of barley for pigs, especially poorer quality barley. |
