Fig. 2

Associations among the transcriptome networks (gene modules), calf phenotypic traits (concentration of VFAs, papillae length and width, calf age) and bacterial composition (taxonomy—genus level). a Number of differentially expressed genes between each pairwise comparison during postnatal period. b Relationship between gene modules (gene modules are defined as M1–M29) and calf phenotypic traits. Gene modules obtained using weighted gene co-expression network analysis and eigengene/PC1 value of each gene module is correlated with the calf phenotypic traits. c Association between the host genes co-expressed in the M10 module and rumen content-associated bacterial genera relative abundance. d Bacterial clusters associated with ion binding-related genes co-expressed in the M10 module. Cluster 1 (Bacteroides, Ruminococcus, Propionibacterium, Klebsiella, Prevotella) positively correlates to the expression of the ion binding-related genes (P < 0.05, r ≥ 0.5). Cluster 6 (Pectobacterium, Bordetella, Mycobacterium, Bartonella, Brachyspira, Ralstonia, Actinobacillus, Leptospira, Tannerella, Leuconostoc, Escherichia, Selenomonas, Francisella, Gallibacterium) negatively correlates to the expression of the ion binding-related genes (P < 0.05, r ≤ − 0.5). Heatmap is generated using Pearson’s correlation value between the expression of a gene and the relative abundance of a bacterial genus. Blue represents positive correlations, whereas yellow represents negative correlations. Numerical values represent the identified bacterial clusters based on their associations with the expression of genes