Fecal Microbiota Transplantation Reduces Colonization in Young Broiler Chickens Challenged by Oral Gavage but Not by Seeder Birds.

spp., particularly and , are major food safety concerns, transmitted to humans mainly via contaminated poultry meat. In a previous study, we found that some commercial broiler farms consistently produced -free flocks while others consistently reared -colonized flocks, and significant differences in the gut microbiota compositions between the two types of farm categories were revealed. Therefore, we hypothesized that gut microbiota influences colonization in poultry and that the microbiota from -free flocks may confer colonization resistance to in the chicken intestine. In this study, two fecal microbiota transplantation (FMT) trials were performed to test the hypothesis. Newly hatched chicks were given FMT via oral gavage of the cecal content of -free adult chickens (treatment groups) or PBS (control groups) before the feed consumption. Approximately two weeks after the FMT, the birds were challenged with either by oral gavage (trial 1) or by co-mingling with -colonized seeder birds (trial 2) to evaluate the potential protective effect of the FMT. Cecal contents were collected (3 times, 5 days apart) to determine the colonization levels via culture and microbiota compositions via 16S rRNA gene sequencing. FMT reduced cecal colonization significantly (log 1.2-2.54 CFU/g) in trial 1 but not in trial 2, although FMT significantly impacted the diversity and compositions of the gut microbiota in both trials. Several genera, such as , , , , , , and , had increased abundance in the FMT-treated groups in both trials. Furthermore, abundance was found to be negatively correlated with the and genera. These findings indicate that even though FMT with adult cecal microbiota can positively affect the subsequent development of the gut microbiota in young broilers, its inhibitory effect on colonization varies and appears to be influenced by the challenge models.