Protective effect of Lactobacillus reuteri KUB-AC5 against Salmonella Enteritidis challenge in chickens

Poultry is an important high-quality food and protein source for humans. However, chicken is considered a primary source of foodborne diseases, especially Salmonella Enteritidis infection. Reducing Salmonella contamination in live poultry will thus lower the risk to consumers. Our previous studies reported that Lactobacillus reuteri KUB-AC5 can produce a substance with antimicrobial activity against pathogenic bacteria, especially Salmonella. In vivo testing revealed that this strain greatly influenced the ileal microbiota by improving chicken gastrointestinal health and inhibiting certain pathogenic bacteria. However, its activity against Salmonella in chicken is unknown. This study investigated the effects of the probiotic L. reuteri KUB-AC5 at various concentrations against Salmonella and the microbiota status in the gastrointestinal tract of broiler chickens. Four treatments groups were used: negative-control group (no Salmonella challenge), positive-control group (Salmonella challenge), and 5 or 7 log cfu probiotic supplementation to Salmonella-challenged chickens. The resultant microbial diversities at the growing and finisher stages were not significantly different among the groups (P>0.05). However, a high dosage of KUB-AC5 maintained similar microbial diversity in Salmonella-challenged chickens as observed in the non-challenged group in the early stage. The exposure Salmonella can affect the microbial diversity that consequently contributes to the disease progression in chicken. Low and high dosages of KUB-AC5 eliminated S. Enteritidis from the ileum and caecum at 14, 21 and 35 days of age. A high-dose of KUB-AC5 also enhanced Lactobacillaceae levels in the growing stage in both the ileum and caecum and suppressed Enterobacteriaceae levels in the finisher stage on day 35, whereas these effects were not observed in the low dose of KUB-AC5 or control groups. These results support the potential value of high-dose L. reuteri KUB-AC5 supplementation for three days after hatching in preventing Salmonella infection in chickens.