CONCLUSION

Dietary supplementation with FCs exerted distinct effects on productive performance, intestinal physiology, oxidative status, and cecal microbial ecology in commercial laying hens. Among the evaluated additives, potato RS consistently produced the most pronounced beneficial responses. Birds receiving RS exhibited improved productive efficiency, as reflected by a lower FCR (1.56 vs. 1.59 in the D1-Control group), while maintaining egg production comparable to that of unsupplemented hens. Moreover, RS supplementation markedly reduced intestinal permeability, as evidenced by lower serum FITC-d concentrations (101.89 vs. 380.99 ng/mL), increased antioxidant capacity (1731.16 vs. 1686.54 µmol TE/mL), and decreased lipid peroxidation (0.25 vs. 0.39 µmol MDA/mL). Dietary supplementation with MOS and FOS also improved specific aspects of intestinal morphology, whereas FOS increased microbial diversity. Furthermore, RS promoted the enrichment of beneficial taxa, including Lachnospiraceae, Blautia, Ligilactobacillus aviarius, and Lactiplantibacillus plantarum_,_ suggesting enhanced fermentative activity and a potential increase in SCFA production.

From a practical perspective, these findings indicate that potato RS is a promising nutritional strategy to improve intestinal health and feed efficiency in laying hens without adversely affecting productive performance. Such an approach may help reduce dependence on antibiotic growth promoters and support more sustainable poultry production systems.

A major strength of this study was the comprehensive comparison of structurally distinct FCs under identical experimental conditions, integrating productive performance, intestinal permeability, oxidative status, intestinal morphology, and cecal microbiota profiling. This multidimensional approach provided novel insights into the relationships between microbial modulation and host physiological responses in commercial laying hens.

Nevertheless, several limitations should be acknowledged. The experiment was conducted under controlled conditions without intentional sanitary or environmental challenges, and microbial functionality was inferred from taxonomic profiles generated by 16S rRNA gene sequencing. In addition, SCFAs, inflammatory mediators, and molecular markers associated with intestinal barrier function were not directly quantified.

Therefore, future studies should evaluate these prebiotics under commercial challenge conditions and incorporate metabolomic, transcriptomic, and immunological approaches to clarify the mechanistic links between microbial alterations and host responses. In particular, quantification of SCFAs and the expression of tight junction proteins and antioxidant-related genes would provide a more comprehensive understanding of the biological effects of FC supplementation.

Overall, the present findings demonstrate that structurally distinct FCs differentially modulate intestinal physiology and microbial communities in laying hens. Among the evaluated additives, potato RS exhibited the most consistent and favorable effects on intestinal integrity, antioxidant status, microbial composition, and feed efficiency, highlighting its potential as an effective dietary intervention for promoting intestinal health and sustainable egg production.