Fig. 1

Overview of experimental design. Eight male C57BL/6 mice from two mother mice were housed in three different cages. Littermates, My^* and V^*, and N and U were co-housed in cage 1 and cage 3, respectively, while littermates E^* and S^* were co-housed together with littermates J and Ms in cage 2. Sample name with and without asterisk indicates littermates of mother mouse 207H and 189C, respectively. Fecal samples of each mouse were collected on the 1st, 2nd, 3rd, 9th, 10th, and 11th day after weaning. Samples from the 1st and 2nd day as well as the 9th and 10th day after weaning were respectively pooled for metagenomic sequencing. Samples from the 3rd and 11th day were subjected to metaproteomic analysis separately