Non-starch polysaccharides (NSP), if not reduced by enzyme supplementation, are hypothesized to promote growth of micro flora and reduce broiler chick performance. Due to concerns 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 chick performance. A broiler chick (male; n=768) bioassay was used to evaluate 36 wheat — based diets (75% wheat inclusion with 35% basal diet containing 1% acid insoluble ash marker by final diet weight). The diets were designed to compare processing (pellet wheat and reground vs ground wheat), enzyme supplementation (0, 250, 500 and 2000 U Avizyme 1300/kg), antibiotic (none, Monencin, Liavomycin and Salinomycin) effect on growth, feed intake, feed: gain, ratio AME and gut development up to 24 days of age. All levels of enzyme supplementation significantly (P< 0.05) increased body weight of broilers fed with wheat — based diets. There were no significant differences in body weight among enzyme levels (250 to 2000 mg/kg). Feed intake from day 0 to 24 was highest (P< 0.01) with 2000 mg/ kg enzyme supplementation. Feed: gain ratio was significant impacted by an interaction between feed processing and enzyme supplementation, but not enzyme level. AME of the diets was 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 antibiotic.
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