Indigestible carbohydrates alter the intestinal microbiota but do not influence the performance of broiler chickens

Aims: Prebiotics are a potential alternative to in-feed antimicrobials to improve performance of chickens. We investigated the effects of mannanoligosaccharide (MOS) and fructooligosaccharide (FOS) on growth, performance and the intestinal microbiota. Methods and Results: Cobb 500 birds were fed either: Control, starter diet without antimicrobials; ZnB, Control + 50 ppm zinc bacitracin; MOS, Control + 5 g kg^-1 MOS; or FOS, Control + 5 g kg^-1 FOS. An energy metabolism study was conducted and intestinal microbial communities assessed by T-RFLP and Lac PCR-DGGE. Diet did not influence performance. Ileal microbial communities were significantly different in ZnB-fed birds compared to all diets, and FOS-fed chickens compared to Control. MOS-fed chickens had a different caecal profile to ZnB and FOS-fed birds. Consensus Lac PCR-DGGE profiles indicated Lactobacillus communities clustered according to diet with Lactobacillus johnsonii characteristic of ZnB diet. Control and MOS-fed chickens displayed significantly different jejunal Lactobacillus profiles to each other whilst ileal profiles were different between MOS and FOS-fed birds. Conclusion: Prebiotics influenced the intestinal microbiota, but did not affect performance. Significance and Impact of the Study: In light of pressure for in-feed antimicrobial withdrawal, the impact of alternative compounds on the intestinal microbiota and bird performance is critical to the poultry industry.