Microbiota of the chicken gastrointestinal tract: influence on health, productivity and disease

Recent advances in the technology available for culture-independent methods for identification and enumeration of environmental bacteria have invigorated interest in the study of the role of chicken intestinal microbiota in health and productivity. Chickens harbour unique and diverse bacterial communities that include human and animal pathogens. Increasing public concern about the use of antibiotics in the poultry industry has influenced the ways in which poultry producers are working towards improving birds' intestinal health. Effective means of antibiotic-independent pathogen control through competitive exclusion and promotion of good protective microbiota are being actively investigated. With the realisation that just about any change in environment influences the highly responsive microbial communities and with the abandonment of the notion that we can isolate and investigate a single species of interest outside of the community, came a flood of studies that have attempted to profile the intestinal microbiota of chickens under numerous conditions. This review aims to address the main issues in investigating chicken microbiota and to summarise the data acquired to date.