Compositional variations in wheat brans influence growth performance, nutrient retention and cecal microbiome in broilers

Due to different flour milling processes, WB were highly variable in starch, protein and fiber contents. This study aimed to identify the key chemical compositions to regulate the growth performance and digestion in broilers. The principal component analysis of 9 chemical variables in 8 WB samples showed the first component explaining 80% of variation positively correlated with fiber components and negatively correlated with starch. Consequently, WB were grouped as low-fiber (LFWB), medium-fiber (MFWB) and high-fiber (HFWB) WB. Five samples were randomly selected from each group to prepare 5 experimental diets by replacing 3% of the corn and soybean meal in the basal diet. On d 7, 324 broiler chicks were divided into 6 treatments with 6 replicates, fed with the corn-soybean meal basal diet (CON) or one of the 5 experimental diets until d 21. Then all birds switched to the same finisher diet for 7 d. Total excreta were collected on d 17 and d 24 for 72 h, respectively. When birds were on the experimental diets, BW, ADG and ADFI did not differ among treatments on d 21 (P < 0.05). The total tract retention (TTR) of DM (P = 0.001) and GE (P = 0.005) were lower, but the TTR of NDF (P < 0.001) were greater in the HFWB than the CON group. After birds switched to the same diet on d 21, the TTR of CP (P = 0.05) and NDF (P = 0.059) was greater in the LFWB group than the CON and HFWB groups. Analyses of cecal microbiota revealed that the LFWB group had lower Chao1 and ACE indices than the other groups, lower Shannon index but higher Simpson index than the MFWB group (P < 0.05). The LFWB group enriched with Barnesiella, while the MFWB group enriched with Lachnospiracea. In conclusion, adding moderate amount of WB with low fiber content was beneficial for broilers by promoting immunoregulatory intestinal microbiota and digestion in broilers.