Characterizing the gut microbiome of broilers raised under conventional and no antibiotics ever practices

Meat from broilers raised without the use of antibiotics is becoming increasingly popular among consumers. Consequently, interest in the microbial profiling of chickens produced under nonconventional practices is growing, however, research on this topic is lacking. The current study was designed to characterize the dynamics of gut microbial populations of broilers raised under conventional and no antibiotics ever (NAE) practices. Four commercial farms (2 conventional and 2 NAE) were included in this study. On each farm, cecal (n = 224) and ileal (n = 224) contents were collected from birds at different stages during the grow out of a single flock and following transportation to the processing facility. Cecal microbiota was dominated by the genera Escherichia and Enterococcus upon hatching in both conventional and NAE flocks, shifting with time toward predominantly Faecalibacterium and Bacteroides. The composition of cecal microbial communities of NAE broilers was different than that of conventional chickens (P ≤ 0.05). Conventional broilers harbored a rich, but less diverse cecal microbiota than NAE, while the ileal microbiota was primarily populated with genera previously named Lactobacillus, which exhibited a higher abundance in NAE broilers (P ≤ 0.05). In both production systems, the microbiota followed a similar temporal succession that was more evident in the ceca. Transportation to the processing plant impacted the microbial composition of the ileum (P ≤ 0.05), characterized by an increase in the relative abundance of Psychrobacter. Finally, differential abundance analysis showed a positive correlation between Campylobacter and Enorma within the cecum microbiota, and a negative correlation with Salmonella.