Taxonomic and functional profiles of gastrointestinal microbiome is constrained by GIT region and developmental age in goat kids. a, alpha diversity indicated by Shannon at the MAG (taxonomy) and gene (function) levels; b, PCoA analysis based on bray–Curtis dissimilarity. The microbial samples from GIT regions were indicated as different shapes, and various developmental ages were indicated by filling colors; c, stream graph displaying of phyla and COG functions along the 124 GIT samples. The X-axis indicates the samples clustered by the sampling sites along the GIT. The Y-axis indicates the relative abundances of the phyla and COG functions in each sample. a, RNA processing and modification; b, chromatin structure and dynamics; c, energy production and conversion; d, cell cycle control, cell division, chromosome partitioning; e, amino acid transport and metabolism; f, nucleotide transport and metabolism; g, carbohydrate transport and metabolism; h, coenzyme transport and metabolism; i, lipid transport and metabolism; j, translation, ribosomal structure, and biogenesis; k, transcription; l, replication, recombination and repair; m, cell wall/membrane/envelope biogenesis; n, cell motility; o, posttranslational modification, protein turnover, chaperones; p, inorganic ion transport and metabolism; q, secondary metabolites biosynthesis, transport, and catabolism; r, general function prediction only; s, function unknown; t, signal transduction mechanisms; u, intracellular trafficking, secretion, and vesicular transport; v, defense mechanisms; w, extracellular structures; y, nuclear structure; z, cytoskeleton.