Abstract: [Objective] The aim of the present study was to assess the effects of dietary supplementation of Chinese herbal medicines on nutrient apparent digestibility, serum biochemical indices and cecal microflora of broilers. [Method] The feeding experiment was carried out with a one-factor completely randomized design. A total of 576 one-day-old male healthy Kebao 505 white-feathered broilers with similar weights were randomly allocated to 8 groups （A-H）. There were 6 replicates in each group and 12 broilers in each replicate. Group A served as a control and fed the basal diet, and the groups B-H fed the same basal diets adding 0.48 g/kg florfenicol, 1.5% Radix isatidis, 1.5% Folium isatidis, 1.5% Indigo naturalis, 0.75% Radix isatidis+0.75% Folium isatidis, 0.75% Radix isatidis+0.75% Indigo naturalis, and 0.75% Folium isatidis+ 0.75% Indigo naturalis, respectively. The feeding experiment which lasted for 42 days was composed of an early stage （1-21 days of age） and a late stage （22-42 days of age） according to the ingredient compositions and nutrition levels of the basal diets. The fecal samples of the broilers at 39-41 days of age were collected to measure the apparent digestibility of major nutrients. The blood samples of the broilers at 42 days of age were collected to determine the biochemical indices. The cecal chyme samples of the broilers in groups A, B and F at 42 days of age were collected to evaluate the microbial diversity and abundance. [Result] Group F had significantly （P<0.05） higher apparent digestibility of nitrogen than the other groups except for group A, had significantly （P<0.05） increased apparent digestibility of dry matter than the other groups except for groups B and G, had significantly （P<0.05） elevated apparent digestibility of energy than groups B, C, D, E and H, had significantly （P<0.05） raised apparent digestibility of calcium than the other groups, and had significantly （P<0.05） improved apparent digestibility of phosphorus than groups C, D, E, G and H. No significant （P>0.05） differences in the serum contents of albumin, total protein, glucose, triglyceride and total cholesterol were observed among the different groups. F group had a significantly （P<0.05） higher Chao1 index of cecal microflora than group A. Firmicutes and Bacteroidetes were the dominant bacterial phyla in cecal chyme samples in groups A, B and F, and the relative abundance of these two bacterial phyla in groups A, B and F were 69.49%, 70.26%, 81.45% and 27.52%, 25.04%, 15.47%, respectively. In addition, Faecalibacterium, Ruminococcaceae_UCG-014, Barnesiella, Bacteroides and Lactobacillus were the bacterial genera that possessed the higher relative abundance. Group F had significantly （P<0.05） increased relative abundance of Firmicutes and significantly （P<0.05） decreased relative abundance of Bacteroidetes than groups A and B. Group B had significantly （P<0.05） reduced relative abundance of Bacteroidetes than group A, and had significantly （P<0.05） elevated relative abundance of Cyanobacteria than groups A and F. Group F had significantly （P<0.05） decreased relative abundance of Actinobacteria than group B. The relative abundance of Faecalibacterium, Barnesiella and Bacteroides in group F was significantly （P<0.05） lower than that in groups A and B, while the relative abundance of Lactobacillus and Ruminococcus_torques_group in group F was significantly （P<0.05） higher than that in groups A and B. The relative abundance of Faecalibacterium and Lactobacillus in group B was significantly （P<0.05） lower than that in group A. There were no significant （P>0.05） differences in the composition of cecal microflora among groups A, B and F. [Conclusion] Dietary supplementation of 0.75% Radix isatidis and 0.75% Folium isatidis exhibited improving effects on the apparent digestibility of major nutrients as well as the diversity and abundance of cecal microflora in broilers.

Key words: broiler, Chinese herbal medicine, feed additive, apparent digestibility, serum biochemical index, caecum, microflora