Dietary non starch polysaccharides (NSP), are hypothesized to promote growth of microflora and reduce broiler chick performance. Because concerns have been raised regarding antibiotic use in poultry feeds, a study was developed to test the effect of enzyme level in combination with or without one of three antibiotics used by the industry on broiler performance. A broiler chick (male; n=768) bioassay was used to evaluate 36 wheat-based diets (75% inclusion with 25% basal diet containing 1% acid insoluble ash marker by final diet weight). The diets were designed to compare processing (pelleted reground wheat vs ground wheat), enzyme supplementation (0, 250, 500 and 2000 mg Avizyme 1300/kg), antibiotic (none, monensin, flavomycin and salinomycin) effect on growth, feed intake, feed:gain, AME and gut development to 24 d of age. All levels of enzyme supplementation significantly (P<0.05) increased body weight of broilers fed wheat-based diets; there were no significant differences in body weight among enzyme levels 250 to 2000 mg/kg. Feed intake (0 to 24 d) was highest (P<0.01) with 2000 mg/kg enzyme supplementation. Feed:gain was significantly impacted by an interaction between feed processing and enzyme supplementation, but not enzyme level. AME of the diets were influenced by enzyme level and feed processing, but not by antibiotic supplementation. Antibiotic supplementation had no significant effect on body weight, feed intake, fore-gut digesta viscosity or nitrogen retention. Nitrogen retention (%) was significantly impacted by all dietary treatments, except antibiotics. Gut development was influenced by feed processing and enzyme supplementation. Generally, enzyme supplementation decreased empty wet weight and length of the gut. Enzymes did not change the relative size of the gizzard or liver. No significant interactions between feed enzyme level and antibiotic treatment were observed for any of the variables measured. In fact, the lack of antibiotic response may be
