Relationships between cecum, ileum and litter bacterial microbiomes in a commercial turkey flock, and the impact of penicillin treatment on early bacterial community establishment

Gut health is paramount for commercial poultry production, and methods to assess gut health are critically needed to better understand how the avian gastrointestinal tract matures over time. One important aspect of gut health is the totality of bacterial populations inhabiting different sites of the avian gastrointestinal tract, and associations of these populations with the poultry farm environment, since these bacteria are thought to drive metabolism and prime the host immune system. In this study, a single flock of commercial turkeys was followed over the course of twelve weeks to examine bacterial microbiome inhabiting the ceca, ileum, and corresponding poultry litter. Furthermore, the effects of low-dose, growth-promoting penicillin treatment (50 g/ton) in feed on the ileum bacterial microbiome were also examined during the early brood period. The cecum and ileum bacterial communities of birds shifted independently but in parallel to one another over time, with distinct bacterial populations harboring each site. Corresponding poultry litter more closely represented the ileal bacterial populations than cecal bacterial populations, and also changed parallel to ileum bacterial populations over time. Penicillin applied at low doses in feed significantly enhanced early weight gain in commercial poults, and this correlated with predictable shifts in the ileum bacterial populations in control versus treatment groups. Overall, this study demonstrates the dynamic shifts in the turkey gastrointestinal microbiome during development, the correlations between bacterial populations in the gastrointestinal tract and the litter environment, and the impact of low-dose penicillin on the modulation of bacterial communities in the ileum. Alternatives to low-dose antibiotics would benefit by mimicking these effects in the gut, among others.