Prophylactic impact of cecal fermentation broth against gut microbiota dysbiosis of broiler chickens challenged with Escherichia coli

The intestinal microorganisms make an important contribution to the development of the host immune system and resistance to pathogen infections, especially early in life. Our previous study found that early inoculation with cecal fermentation broth could change the colonization patterns of intestinal microorganisms and enhance the immune performance in broilers. However, it remains unknown whether cecal fermentation broth inoculation can be used as a novel form of treatment against pathogenic infections. In this study, a pathological model of avian pathogenic Escherichia coli (E. coli) was established to investigate the mechanism of cecal fermentation broth against pathogen infection in broilers. A total of 180 newly hatched broilers were randomly divided into three groups: (1) negative control (Con) group, inoculated with sterile normal saline from 1 to 4 days of age; (2) positive control (NS + E.coli) group, inoculated with sterile normal saline from 1 to 3 days of age, infected with E.coli at 4 days of age; (3) fermentation broth prevention (FerB + E.coli) group, inoculated with fermentation broth from 1 to 3 days of age, infected with E.coli at 4 days of age. Subsequently, 8 individuals were randomly selected from each group for weighing followed by slaughter to determine relevant indicators at 7, 10, 14 and 21 days of age. The results showed that early inoculation with fermentation broth significantly alleviates the negative effects on growth performance and intestinal permeability caused by E. coli infection. Furthermore, enhanced small intestinal health was observed, as indicated by the increase in villus height and the ratio of villus height to crypt depth (V/C). The relative abundance of Bacteroidetes was higher in the prevention group, and the number of functional genes detected was significantly greater. Additionally, the concentration of propionic acid was substantially elevated in the prevention group, while butyric acid concentrations were significantly reduced in the challenge group. This study demonstrates that early intervention with cecal fermentation broth improves intestinal barrier function and immune performance in broilers by increasing the relative abundance of intestinal Bacteroides and promoting propionic acid synthesis. These findings provide a novel strategy for preventing intestinal inflammatory disorders in broilers, such as avian colibacillosis.