The development of the chicken intestinal microbiome after topical application of adult caecal content to the egg surface

The study aimed to observe the development of the ileal and caecal microbiomes in chicks between 0 and 14 days post hatch (d.p.h). A total of two experiments were run in which diluted adult caecal content was sprayed on incubating eggs at 2, 7, 14 and 18 days of incubation. A negative control group was included to observe microbiome development without the intervention. Samples were taken from the ileum and caecum at 3 and 7 d.p.h (Experiment One) and 0, 3, 7 and 14 d.p.h (Experiment Two).