Lactobacillus plantarum improves gut microbiota, metabolism, and performance in laying hens.

Probiotics, particularly Lactobacillus species, benefit poultry by modulating the intestinal microbiota and enhancing host nutrient metabolism. In this study, a Lactobacillus plantarum (LP) was administered via drinking water to Hy‒Line Brown laying hens over a 42‒day period. Compared with the control group, probiotic‒treated hens exhibited significantly improved laying performance and egg quality. 16S rRNA gene sequencing revealed that the probiotic significantly increased the relative abundance of beneficial Lactobacillus and reduced potentially pathogenic genera in the intestinal tract. Untargeted metabolomic analysis demonstrated elevated levels of nutritionally important unsaturated fatty acids (oleic acid and linoleic acid) and essential amino acids (L‒tryptophan, L‒lysine, and L‒valine) in the treatment group. Pearson correlation analysis further revealed significant positive associations between Lactobacillus abundance and these key metabolites. These findings demonstrate that drinking water‒administered LP effectively enhances poultry health, egg quality, and production performance through modulation of the gut microbiota‒metabolite axis, suggesting its potential as a precision nutrition strategy in laying hen production.