Degradation of cell wall polysaccharides by combinations of carbohydrase enzymes and their effect on nutrient utilization and broiler chicken performance.

In vitro incubation studies were carried out to determine if various carbohydrase preparations contained appropriate activities to target nonstarch polysaccharides (NSP) of wheat, soybean meal (SBM), canola meal, and peas. Triplicate samples (0.1 g) were incubated with a number of carbohydrase preparations (i.e., cellulase, pectinase, xylanase, glucanase, galactanase, and mannanase) or their combinations at 45 degrees C and pH 5.2. A more pronounced degradation of NSP was achieved when the enzyme preparations were used in concert. When compared with the control (nonenzyme treatment), the highest degree of NSP degradation reached was 37% for wheat, and 36, 26, and 28% for canola meal, SBM, and peas, respectively. Four enzyme combinations were studied further in a 2-wk (5 to 18 d of age) growth performance and nutrient digestibility trial with broiler chickens. All enzyme combinations were effective in improving (P < 0.05) weight gain, feed-to-gain ratio, AMEn, apparent ileal digestibilities of starch and protein, and apparent total tract digestibility of NSP in birds fed a wheat, wheat screening, SBM, canola meal, and peas-based diet. The most complex enzyme combination was found to be superior (P < 0.05) to others in improving ileal protein digestibility and feed-to-gain ratio. The effectiveness of this combination in elimination of the nutrient-encapsulating effect of cell walls was further evaluated in a balance study with adult roosters fed a conventionally ground full-fat canola seed. Enzyme addition increased (P < 0.05) NSP digestibility from 11.1 to 30.1%, which, in turn, resulted in a marked increase (P < 0.05) in TMEn value (4.176 vs 4.744 Mcal/kg) of the seed. It is evident from the present studies that the addition of an appropriate combination of carbohydrase enzymes to target cell wall polysaccharide structures could further improve enzyme efficacy in practical wheat, SBM, canola meal, and peas-based broiler diets.