A study was designed to determine the effects of enzyme supplementation on poults fed commercially based diets which included; corn, soybean meal (SBM), ground wheat with meat and bone meal (0-21 days) or propak (22-56 days). Day old turkey poults (n=3850) were randomly divided into 35 pens and fed one of five dietary treatments for 56 days. Performance parameters, feed intake (FI), average daily gain (ADG), feed conversion ratio(FCR) and mortality, were evaluated for the following periods: 0-4 (1A), 4-8 (2A), 8-12 (3A), 12-16 (4A), 16-21 (5A), 0-21 (A), 21-42 (B) and 42-56 (C). In addition, ileal contents along with duodenal, jejunal and ileal (n=7/trt) sampling occurred during the afore mentioned periods. Significance was determined at P < 0.05. Treatments included: a positive control (PC), a negative control (NC) (corn matrix adjustment of 140 kcals), and NC diets supplemented with Avizyme^&#174;1502 (AZ) at; 250, 500 or 750g/MT. Avizyme treatments significantly improved ADG over the PC during periods 2A, 3A, A and B. However, period 1A had significant decreases in ADG with enzyme inclusion. Period B experienced FCR improvement with AZ. Both energy and protein ileal digestibility were decreased with enzyme inclusion during periods 1A, 2A, 3A, 4A, 5A, A and B. Villus height and crypt depth did not respond to dietary treatment, though a significant interaction of age and villus height occurred. Villus heights were similar during periods A and B; however, from period B to C, villus height dramatically increased in the PC diet over other treatments. / Master of Science