CML352 Isolated from Chinese Local Breed Chicken Modulates the Gut Microbiota and Improves Intestinal Health and Egg Quality in Late-Phase Laying Hens.

strains with fine probiotic properties are continuously needed in the laying hen industry to improve the animals' gut health and production performance. In this study, we isolated 57 strains from the gut microbiota of 17 different chicken breeds in China. We characterized the probiotic features of these isolates, and evaluated the effects of a selected strain, CML352, on the production performance and gut health of the late-phase laying hens. The results showed that the isolates varied much in probiotic properties, among which CML352 displayed high acid and bile salt tolerance, high hydrophobicity, auto-aggregation, and antibacterial activities. Whole genome sequencing analysis showed that CML352 was closely related to a strain isolated from human fecal samples, but had different functional potentials. Dietary supplementary of CML352 significantly reduced the Firmicutes to Bacteroidetes ratio, increased the expression of , and decreased the expression of , , and . Furthermore, strain CML352 reduced the birds' abdominal fat deposition, and improved egg quality. Taken together, this study indicated that the newly isolated strain might be a worthy probiotic with positive impacts on the intestinal health and production performance of late-phase laying hens.