Abstract: [Objective] This study was conducted to assess the effects of dietary supplementation of compound enzyme and probiotic preparations on growth performance, serum biochemical indices and antioxidant capacity, and small intestinal morphological development of AA broilers. [Method] A total of 480 one-day-old male AA broilers with similar weights were randomly assigned into a control group and 3 treatment groups （T1, T2, T3）. The control group fed a corn-soybean meal based diet, while the T1, T2 and T3 groups fed the same basal diets containing 0.2 g/kg compound enzyme preparation, 1 g/kg compound probiotic preparation, and 0.2 g/kg compound enzyme preparation+1 g/kg compound probiotic preparation, respectively. There were 6 replicates in each group and 20 broilers in each replicate. The feeding trial lasted for 42 days. The average daily feed intake （ADFI）, average daily gain （ADG）, and feed to gain ratio （F/G） at different growth stages （1-21 days of age, 22-42 days of age, 1-42 days of age) were calculated. On the 21^st and 42^nd day of the trial, blood samples were collected to determine the serum biochemical indices and antioxidant capacity. Samples of duodenum, jejunum and ileum were collected to prepare tissue sections. The villus height （VH） and crypt depth （CD） of each small intestinal segment was observed after HE staining, and the ratio of villus height to crypt depth （V/C） was calculated. [Result] ① Compared with the control group, significantly （P<0.05） higher weight at 21 days of age, ADFI and ADG at 1-21 days of age, and ADG at 1-42 days of age were observed in T1 and T3 groups; T1 group had significantly （P<0.05） increased ADFI at 22-42 days and 1-42 days of age, and had significantly （P<0.05) decreased F/G at 1-42 days of age; the F/G at 1-21 days, 22-42 days and 1-42 days of age in T2 group was significantly （P<0.05） reduced; T3 group had significantly （P<0.05） decreased F/G at 22-42 days and 1-42 days of age. The weight at 21 days of age as well as the ADFI and ADG at 1-21 days and 1-42 days of age in T1 and T3 groups were significantly （P<0.05） higher than those in T2 group. The F/G at 1-21 days and 22-42 days of age in T2 group was significantly （P<0.05） lower than that in T1 and T3 groups, and the F/G at 1-42 days of age in T2 group was significantly （P<0.05） lower than that in T1 group. ② Significantly （P<0.05） reduced serum TG content at 21 days and 42 days of age in T1, T2 and T3 groups was observed compared with the control group. T3 group had significantly （P<0.05） elevated serum TP content at 42 days of age than that of the control group and T2 group. T1 group had significantly （P<0.05） higher serum GLU content at 42 days of age than that of the other groups. ③ There were no significant （P>0.05） differences in serum antioxidant capacity at 21 days and 42 days of age among the 4 groups. ④ Compared with the control group, T1, T2 and T3 groups had significantly （P<0.05） lower CD and significantly （P<0.05） higher V/C of duodenum and ileum; T1 and T3 groups had significantly （P<0.05） increased VH of duodenum; T3 group had significantly （P<0.05） elevated VH of jejunum; T2 and T3 groups had significantly （P<0.05） reduced CD of jejunum. The VH and V/C of duodenum in T1 and T3 groups was significantly （P<0.05） higher than that in T2 group. The VH of jejunum in T3 group was significantly （P<0.05） higher than that in T1 and T2 groups. The CD of jejunum in T1 group was significantly （P<0.05） lower than that in T2 group. The CD of ileum in T3 group was significantly （P<0.05） lower than that in T1 group. [Conclusion] Exclusive or combined supplementation of compound enzyme and probiotic preparations in diet exhibited favorable effects on growth performance, serum biochemical indices and antioxidant capacity, and small intestinal morphological development of AA broilers. The combined supplementation showed a better comprehensive performance.

Key words: broilers, compound enzyme preparation, compound probiotic preparation, growth performance, serum biochemistry, small intestinal morphological development