Abstract: Four enzyme preparations (E1，E2，OT，Xylanase) were evaluated by animal feeding trial using wheat-type diets for growing pigs. Using a single factor design，112 heads of crossbred (Landrace×Yorkshire) piglets about 19.34 kg were selected and divided into 7 treatments (4 duplicates per treatment and each duplicates had 4 piglets with the male/female=1∶1) randomly，to investigate the effect of different enzymes on performance of growing pigs．The duration of feed trial was 8 weeks，and divided into three phases (week 0 to 2；2 to 4；4 to 8 respectively). The diets were as follows：corn-based diet,wheat-based diet, wheat-based diet with E1,E2,OT and xylanase separately,lower-energy wheat-based diet with OT enzyme．Furthermore,
another 6 heads of crossbred (Landrace×Yorkshire) barrows about 20 kg fitted with a simple “T” cannula at the terminal ileum were selected and conducted in a 6×6 Latin Square design to assay the apparent feces digestibility and ileal digestibility using AIA.The results indicated that adding enzymes can improve the ADG compared with wheat-based diet, and have the tendacy to improve the ADG during the week 2 to 4 (P=0.10). There is no significant effect on the ADG of E1 treatment in whole trail (P>0.05).Other enzymes can increase the ADG significantly(P<0.05) and OT treatment (P<0.01) had higher ADG than the control treatment. Adding enzymes to wheat-based diet can significantly decrease the F/G in whole trail(P<0.05)，and significantly decrease the diarrhea ratio from 4 to 8 weeks and the whole trial (P<0.05).E2，OT，Xylanase treatment get to positively significant level(P<0.01). Compared with wheat-based diet, enzymes had no significant effect on apparent feces digestibility of CP and Energy for growing pigs (P>0.05). Enzymes supplementation had the tendacy to improve the apparent ideal digestibility of energy (P=0.10).E2，OT，Xylanase can significant improve the apparent ileal digestibility of CP(P<0.05), but there was no significant effect by adding E1(P>0.05). 

Key words: wheat; enzyme preparations; performance; nutrient digestibility; growing pig