Effect of a combination of xylanase, amylase and protease on growth performance of broilers fed low and high fiber diets

Abstract This study evaluated the effect of a combination of xylanase, amylase, and protease (XAP; providing 2000 U of xylanase, 200 U of amylase, and 4000 U of protease per kg diet) in low and high fiber diets on growth performance of Cobb 500 broilers from d 0 to 21 of age. A 2 × 2 factorial design with 8 replicate floor pens (8 birds/pen; in two batches) was used. The treatments included 2 fiber levels: low fiber diets based on corn and soybean meal (SBM) and high fiber diets with addition of wheat, wheat middling, canola meal and distillers dried grains with solubles (DDGS). Each level of fiber diet was supplemented without or with XAP. All the test diets contained 500 FTU/kg phytase in the background and were pelleted. In overall study period (d 0–21), the high fiber diet increased FCR ( P   0.05) by 0.04 units compared with low fiber diet. The XAP supplementation increased ADG by 12% and reduced FCR by 0.09 units compared with control diet ( P P P  > 0.05) effect on ADG and FCR. The XAP supplementation improved ADFI in low fiber diet but did not affect ADFI in high fiber diet. A significant ( P   0.01) interaction was observed between fiber and XAP for FCR in the first week where XAP reduced FCR by 0.27 and 0.05 units, respectively in high and low fiber diets. Overall, the FCR response to XAP is more pronounced in high fiber diets than in low fiber diets, especially during the first week. The results suggest that the addition of XAP can optimize the utilization of fiber for better ADG and feed efficiency in broilers, maintaining performance to a level comparable to that of the costly conventional low fiber diet.