Effects of wheat bran in comparison to antibiotics on growth performance, intestinal immunity, barrier function, and microbial composition in broiler chickens

This experiment was conducted to evaluate the effects of wheat bran (WB) and antibiotics on growth performance, intestinal immunity, barrier function, and microbial composition in broiler chickens. A total of 168 one-day-old male Arbor Acre chicks were allocated to 3 treatments consisting of 7 replicates with 8 birds per replicate. The 3 treatments were: an antibiotic-free control diet (control, CON), CON 1 75 mg/kg chlortetracycline as an antibiotic growth promoter (AGP), and CON 1 3% WB. Birds fed AGP and WB had greater (P < 0.05) ADG during days 1 to 21 and lower (P < 0.05) feed-to-gain ratio during each phase than those fed CON. The WB supplementation reduced (P < 0.05) serum concentrations of tumor necrosis factor-a and diamine oxidase activity compared with CON on both day 21 and 42. The AGP and WB supplementation decreased (P < 0.05) interleukin-1 beta concentration in jejunal mucosa on day 21 and increased (P < 0.05) secretory immunoglobulin A concentration in jejunal mucosa on day 21 and 42. The relative expression of occludin in jejunal mucosa was upregulated (P < 0.05) in WB than in CON on day 21. Moreover, both AGP and WB supplementation upregulated (P < 0.05) the relative expression of zonula occludens-1 in jejunal mucosa on day 21 and 42. The WB supplementation enhanced the a-diversity of cecal microbiota, as evidenced by the increased Shannon index (P < 0.05). At the phylum level, the phylum Firmicutes was enriched (P < 0.05) in WB. At the genus level, the WB supplementation enriched (P < 0.05) Lachnoclostridium and Butyricicoccus. The WB supplementation increased (P < 0.05) cecal total short chain fatty acids concentrations on day 21 and 42, and butyric acid concentrations on day 42 compared with CON. Collectively, supplementation of 3% WB could promote growth by improving intestinal immunity, barrier function, and microbial composition in broilers. Thus, WB may have a role in replacing antibiotics for improved growth performance and intestinal health in broilers.