This ready to load phyloseq R S4 object contains the ASV table, taxonomy table and sample metadata. This data was build using the DaDa2 (version 1.18.0) and phyloseq (version 1.34.0) R packages using the SILVA 138.1 nr99 database and raw MiSeq PE300 sequencing data deposited at NCBI-SRA under BioProject: PRJNA975731. F. Marcato, J.M.J. Rebel, S.K. Kar, I. Wouters, D. Schokker, A. Bossers, F. Harders, J.W. van Riel, M. Wolthuis-Fillerup and I.C. de Jong. The main goal of the current study was to investigate whether or not it was possible to modulate the fecal microbiome and thereby reducing endotoxin concentrations in the excreta of broiler chickens. An experiment was carried out with a 2 x 2 x 2 factorial arrangement including 3 factors, 1) genetic strain (fast-growing Ross 308 vs. slower-growing Hubbard JA757), 2) no vs. combined use of probiotics and prebiotics in the diet and drinking water, 3) early feeding at the hatchery vs. non early feeding. A total of 624 Ross 308 and 624 Hubbard JA757 day-old male broiler chickens were included until d 37 and d 51 of age, respectively. Broilers (26 chicks per pen) were housed in a total of 48 pens, and there were 6 replicate pens/treatment group. Pooled cloacal swabs (10 chickens per pen) for microbiome and endotoxin analyses were collected at a target body weight (BW) of 200 g, 1 kg and 2.5 kg.