Abstract
Two experiments were conducted to investigate the effects of a combined α-galactosidase and xylanase preparation on nutrients digestibility and growth performance in broiler chickens. Experiment 1 had 240 broilers allocated to 3 treatments with the dietary supplementation of 0, 300 and 500 g/t of the enzyme combination. Diet and amino acid (AA) digestibility were assessed. Experiment 2 was a 2 × 3 (enzyme × diet) factorial arrangement with 10 replicates of 12 male broilers per replicate. Diets were based on corn-Soybean meal (SBM) diet and had 3 nutritional levels (normal, 2% apparent metabolizable energy (AME) and crude protein (CP) reduction, and 4% AME and CP reduction). Each of these diets was fed with or without enzyme supplementation. Growth performance, chyme viscosity, nutrients digestibility, and endogenous enzymes activity were assessed. In experiment 1, enzyme supplementation improved the digestibility of Ca (P = 0.025) and ileal digestibility of total AA, Pro, Alu, Ile, Lys, His, Thr, Glu, Val, Leu, Tyr and Phe (P < 0.05), and also tended to increase the AME of diets (P < 0.10). In experiment 2, broilers fed the corn-SBM diet with 4% nutrient reduction had better growth performance (P < 0.05), jejunal digesta viscosity at 42 days (P < 0.01), and lower digestibility of gross energy (GE) (P < 0.05) when compared to those fed the normal nutrient diet. Enzyme inclusion increased digestibility of CP (P = 0.044), GE (P = 0.009), raffinose (P < 0.001) and stachyose (P < 0.001), improved average daily gain (P = 0.031), and reduced jejunal digesta viscosity at 42 days (P = 0.011). Besides, similar improvements trend in amylase, trypsin, sucrase, and maltase activity with enzyme inclusion were observed as with energy. These data support that the enzyme supplementation increased nutrients and ileal amino acid digestibility, improved performance and endogenous enzymes activity.
Box-Behnken optimisation of growth performance, plasma metabolites and carcass traits as influenced by dietary energy, amino acid and starch to lipid ratios in broiler chickens
