Moreover, differential metabolites in D4W and H4W calves were significantly enriched in pathways related to fatty acid biosynthesis, caffeine metabolism, glycerophospholipid metabolism, choline metabolism in cancer, cutin, suberine and wax biosynthesis, ABC transporters, pathogenic E. coli infection, eicosanoids, glycine, serine and threonine metabolism, alcoholism, biosynthesis of unsaturated fatty acids, aminoacyl-tRNA biosynthesis, and prolactin signaling pathway (Figure 7H, p < 0.05). This evidence concerns the gene PRL and escherichia coli infection.