Dietary fiber plays a crucial role in poultry gut health, with insoluble fibers improving digestive function and soluble fibers enhancing microbial fermentation. This study investigated the effect of various fiber types and combinations on jejunal and cecal microbiota in broilers experiencing subclinical enteric challenge. Eight dietary treatments were tested from hatch: six fiber-supplemented diets and two controls (challenged and unchallenged, both without supplemental fiber). Fiber treatments included 3% oat hulls (OH), 3% soy hulls (SH), and combinations of 1.5% OH or SH with either 1.5% wheat middlings (WM) or sugar beet pulp (SBP). Challenged birds received a tenfold coccidia vaccine dose on d14 and 10⁸ CFU C. perfringens on d18. Jejunal and cecal contents from 9 birds per treatment were collected on d21 for microbiota analysis using shotgun whole genome sequencing. Microbiota data were analyzed using R software (version 4.3.2) with phyloseq, vegan, and DESeq2 packages to assess alpha diversity, beta diversity, and differential abundance. Alpha diversity analyses by calculating Shannon and Simpson indices revealed challenge-induced reductions in cecal diversity (Kruskal-Wallis, P < 0.05), with fiber treatments showing trends toward diversity restoration (Kruskal-Wallis, P = 0.099). The challenge significantly disrupted the cecal community structure (PERMANOVA, P = 0.001) but had a limited impact on the jejunal microbiota. Beta diversity indicated distinct community structures between fiber treatments and challenged control in the cecum but not jejunum. OH+SBP treatment most effectively enhanced Lactobacillus species (L. pontis, log₂FC +5.96; L. fermentum, log₂FC +2.59), while SH+SBP promoted butyrate-producing bacteria including Agathobaculum massiliense (log₂FC +3.25) and Lachnoclostridium sp. (log₂FC +23.52). All fiber treatments significantly reduced potential pathogens, with OH+SBP treatment reducing Escherichia species (log₂FC -25.19), and SH+WM reducing pathogens like Pseudomonas hunanensis (log₂FC -24.11) and Streptomyces species. The pronounced effects in cecum versus minimal effects in jejunum suggest that fiber combinations primarily exert benefits through hindgut fermentation. These findings demonstrate that strategic combinations of soluble and insoluble fibers effectively modulate the cecal microbiota, promoting beneficial bacteria while suppressing potential pathogens and offering a dietary approach to enhance resilience against enteric challenges in broiler production.

Tabish, R., Y.  Lin, S. Rochell, W. Pacheco, M. Bailey, W. Dozier, K. McCafferty and R. Hauck. 2025. Synergistic effects of soluble and insoluble fiber combinations on the jejunal and cecal microbiota of broilers with a subclinical enteric challenge. 2025 Poultry Science Association Annual Meeting, Abstract 94