Fig. 3

Clarification of the ruminal symbiotic microbial metabolic pathway during 3-IAld and PGD2 synthesis. a PCA analysis of metagenomic data based on KEGG functional database (n = 8). b Comparison of microbial domains in the rumen contents of lambs among four groups (n = 8); statistical analysis was performed using the Kruskal–Wallis test, with the FDR < 0.05 being regarded as significantly different. c Pathways of tryptophan metabolism and 3-IAld generation in the ruminal microbiota. A green word or line represented the highest gene abundance in the M group, yellow represented MH, blue represented MC, and brown represented MHC group. d Spearman’s correlation analysis (P < 0.05, |r|> 0.65) between the relative abundance of microbial species and 3-IAld level in the rumen. e The relative abundance of Bifidobacterium species related to tryptophan metabolism. f Pathways of arachidonic acid metabolism and PGD2 generation in the ruminal microbiota; A green word or line represented the highest gene abundance in M group, yellow represented MH, blue represented MC, and brown represented MHC group. g Spearman’s correlation analysis (P < 0.05, |r|> 0.65) between the relative abundance of Candida albicans and PGD2 level in the rumen. h The relative abundance of Candida albicans in the rumen. Statistical analysis was performed using the Kruskal–Wallis test, with the FDR < 0.05 being regarded as significantly different (n = 8). 3H-KYN: 3-Hydroxykynurenine; KYN: Kynurenine; acdA: Acyl-CoA dehydrogenase; ARA: Arachidonic acid; ARAT: Aromatic amino acid aminotransferase; COX1: Cyclooxygenase 1; DGLA: Dihomo-gamma-linolenic acid; fadA: Acetyl-CoA acyltransferase; GLA: Gamma-linolenic acid; IAA: Indole acetic acid; IAAld: Indole-3-acetaldehyde; 3-IAld: Indole-3-carboxaldehyde; IAM: Indole-3-acetamide; ILA: Indole-3-lactic acid; IPA: Indole-3-propionic acid; IPYA: Indole-3-pyruvate; KYNU: Kynureninase; LA: Linolenic acid; PGD: Prostaglandin D; porB, C: pyruvate ferredoxin oxidoreductase B and C; PL: Phospholipids; PLA, B: Phospholipase A and B; TDO: Tryptophan 2,3-Dioxygenase; TMO: Tryptophan 2-monooxygenase; TNA: Tryptophanase; TRA: Tryptamine; trpA, B: tryptophan synthase alpha and beta chain