Pirc rats (F344/NTac-Apcam1137) carry a heterozygous germinal mutation in Apc leading to the spontaneous development of tumours along the intestine, notably in the colon9,10, thus representing a relevant experimental model to study the process of colon tumorigenesis including the influence of external factors or individual host factors, such as the intestinal microbiota11. Here, APC is linked to neoplasm.