Protective effects of dietary betaine on intestinal barrier function and cecal microbial community in indigenous broiler chickens exposed to high temperature environment

High temperature environment causes reduction in productivity in broilers by disrupting the intestinal barrier function. This study aimed to investigate the protective effects of dietary betaine on intestinal barrier function and cecal microbial community in indigenous broilers (Huaixiang chickens) exposed to high temperature environment. A total of 144 5-week-old male broilers (average initial body weight of 401.62 ± 9.51 g) were randomly allocated to three treatments for 10 weeks feeding trial; each treatment contained six replicates with eight birds per replicate. The three treatments included normal temperature control group (NT, fed basal diet, 26 ± 1 °C), high temperature control group (HT, fed basal diet, 32 ± 1 °C for 8 h/day), and HT group supplemented 1000 mg/kg betaine (HTB). The results showed that high temperature environment reduced the Occludin, Claudin-4, and ZO-1 expressions in duodenal mucosa (P < 0.05). Dietary betaine improved the Claudin-4 and ZO-1 expressions of duodenal mucosa (P < 0.05). In jejunal mucosa, HT group had lower Occludin, Claudin-1, Claudin-4, and ZO-1 expressions than NT group (P < 0.05). Compared with HT group, HTB group had higher Occludin and ZO-1 expression (P < 0.05). In ileal mucosa, the relative mRNA expression of ZO-1 in HT group was lower than those in NT group (P < 0.01), and dietary betaine (HTB group) improved ZO-1 expression compared with HT group (P < 0.05). Based on the results of 16S rRNA sequencing, the enriched and dominant microbials in NT group are Epsilonbacteraeota, Bacteroidetes, and Gammaproteobacterial, the enriched and dominant microbial in HT group is Muribaculaceae, and Firmicutes is the enriched and dominant microbial in HTB group. Taken together, the findings revealed that dietary betaine improved the intestinal barrier function and cecal microbial community in indigenous broilers under high ambient temperature.