Jejunal histopathology, metagenome, and mucosal transcriptome of broilers after an enteric challenge and fed diets with different fiber types and concentrations.

This study investigated the efficacy of various dietary fiber sources and combinations in mitigating subclinical enteric infection in broilers. Using a randomized complete block design, 2,160 d-old YP x Ross 708 male broilers were assigned to eight treatments. These included an unchallenged control and a challenged control, followed by six dietary treatments applied to challenged broilers. The dietary treatments consisted of fiber supplementation with oat hulls (OH) or soy hulls (SH), either alone or in combination with wheat middlings (WM) or sugar beet pulp (SBP). Birds were challenged with Eimeria spp. followed by Clostridium perfringens, and a multi-omics approach was employed to analyze jejunal histopathology, microbiome, and host mucosal transcriptome. While the enteric challenge induced significant histopathological changes, fiber combinations including OH-WM and OH-SBP significantly (P < 0.05) reduced cumulative pathology scores. The challenge caused a shift toward Lactobacillus crispatus dominance in the microbiome. Each fiber source altered the microbiome distinctively: OH increased Romboutsia sp., OH-SBP enriched beneficial Limosilactobacillus spp., and SH combinations enhanced butyrate-producing Dysosmobacter welbionis. Transcriptome analysis revealed that fiber supplementation suppressed inflammatory pathways while upregulating cell cycle progression and DNA repair pathways. Integration of bacteriome with host gene expression data revealed coordinated associations, including a link between Glutamicibacter protophormiae, Spirosoma, Eggerthella, and Blautia through host genes APOB, DSEL, and ENPP7, indicating a correlation of fiber-degrading bacteria with host lipid metabolism and extracellular matrix remodeling. These findings suggest that combining insoluble and soluble fibers may create a more resilient gut environment against enteric challenges through complementary mechanisms, with OH based combinations notably exhibiting reduced pathology, stronger anti-inflammatory response and suppression of opportunistic species.