myo ‐Inositol's role in laying hens’ active gastrointestinal microbiota: a strain comparison

BACKGROUND myo ‐Inositol (MI) is a cyclitol involved in cellular metabolism and phytate degradation, yet its influence on the gastrointestinal tract (GIT) microbiota of laying hens remains poorly understood. This study investigated the effects of graded dietary MI supplementation on the active GIT microbial communities of two commercial laying hen strains. RESULTS Lohmann Brown Classic (LB) and Lohmann LSL‐Classic (LSL) hens were fed diets supplemented with 0, 1, 2, or 3 g MI kg −1 feed. Active microbiota were assessed by 16S rRNA gene amplicon sequencing (cDNA‐based) of 623 mucosa and digesta samples from the crop, duodenum, ileum, and ceca. Microbial community composition was primarily shaped by GIT section ( R 2 = 0.43), followed by host strain ( R 2 = 0.03) and sample type ( R 2 = 0.02). MI supplementation explained a smaller proportion of variance but significantly influenced specific taxa, particularly in the crop and ceca. Overall, 66 amplicon sequence variants, including members of Limosilactobacillus , Bacteroides , and Roseburia , differed across MI concentrations. Strain‐dependent responses were observed, with LB hens showing greater separation between mucosa and digesta communities, whereas LSL hens exhibited a higher number of MI‐responsive amplicon sequence variants in the duodenal and ileal digesta. Correlation analyses revealed associations between Ligilactobacillus and egg number and yolk MI concentration, and between Alistipes and egg weight. CONCLUSION Dietary MI supplementation induces localized and strain‐dependent alterations in the active GIT microbiota of laying hens. Although these effects were modest compared with host genotype and GIT section, the findings provide first evidence for MI–microbiota interactions with potential relevance to egg production traits.