The impact of environmental conditions on the gut microbiome of broiler chickens

Knowledge of factors that influence the functioning of gut microbes is essential to improve health and reduce the use of antibiotics in poultry production. The environment, and more specifically housing conditions, can affect the gut microbiome of broiler chickens. The gut microbiome is defined as the collection of all the microorganisms and their "theatre of activity" in the gut environment. Previous research showed that the development of the gut microbiome is hampered in animals raised in high-hygiene environments, such as isolators. It has also been reported that human individuals and animals who live together show less variation in the gut microbiome compared to a group of random individuals. In a Dutch human population, it has been shown that the gut microbiome was primarily shaped by environmental factors and cohabitation. Therefore, a proper understanding of how the composition and functioning of the gut microbiome in broiler chickens is affected by interactions between hosts, and hosts and their environment, is needed. To this end, the effect of environmental factors should be considered in the design, analyses, and interpretation of study outcomes. In addition, knowledge of the development of intestinal microbiome composition and function would be of great value for optimizing the resilience of broiler flocks that can help in reducing the need for therapeutic antibiotics. Although the mechanisms driving gut microbiome development are not fully understood, there is data suggesting that this development is major in the first week post-hatch, and that around three weeks post-hatch, cecal microbiota composition can be considered mature in a commercial well-performing broiler flock. It is important to further study mechanisms underlying gut microbiome development and function to develop better diagnostics and management tools to improve broiler health.