Comparative effects of mannanoligosaccharides, fructooligosaccharides, and potato resistant starch on intestinal integrity, antioxidant status, and cecal microbiota in commercial laying hens.

Functional carbohydrates are increasingly used as alternatives to antibiotic growth promoters because of their ability to modulate intestinal health and microbial populations. However, comparative information regarding the effects of structurally different prebiotic compounds in laying hens remains limited. This study aimed to compare the effects of mannanoligosaccharides (MOS), fructooligosaccharides (FOS), and potato resistant starch (RS) on productive performance, intestinal integrity, antioxidant status, intestinal morphology, and cecal microbiota in commercial laying hens. A total of 200 Babcock Brown laying hens aged 37 weeks were randomly assigned to four dietary treatments for 12 weeks: basal diet without supplementation (D1-Control), basal diet supplemented with MOS (2,000 mg/kg), FOS (700 mg/kg), or potato RS (700 mg/kg). Productive performance parameters were recorded throughout the experiment. Intestinal permeability was assessed using serum fluorescein isothiocyanate-dextran concentrations, while antioxidant status was evaluated through oxygen radical absorbance capacity and thiobarbituric acid reactive substances assays. Intestinal morphology and goblet cell distribution were examined histologically. Cecal microbial communities were characterized using 16S rRNA gene sequencing and bioinformatic analyses. No mortality was observed during the study. Egg production and egg mass were not significantly affected by dietary treatments. However, hens receiving potato RS exhibited the lowest feed conversion ratio (1.56) compared with the control group (1.59; p = 0.028). Dietary supplementation significantly improved oxidative status, with the highest oxygen radical absorbance capacity observed in the RS group (1731.16 µmol TE/mL; p = 0.019), whereas lipid peroxidation was significantly reduced in the FOS and RS groups (p < 0.001). All functional carbohydrates reduced intestinal permeability compared with the control group (p < 0.001), with the greatest reduction observed in the RS group. Supplementation differentially affected intestinal morphology, particularly in the duodenum and jejunum. Microbial analyses revealed significant dietary effects on cecal bacterial communities. FOS increased microbial diversity, whereas RS promoted the enrichment of beneficial short-chain fatty acid-producing taxa, including Blautia and Lachnospiraceae, and increased the abundance of beneficial lactobacilli. Dietary supplementation with functional carbohydrates improved intestinal barrier function, antioxidant status, and cecal microbial composition in commercial laying hens. Potato RS exerted the most pronounced beneficial effects, resulting in improved feed efficiency, enhanced antioxidant capacity, reduced intestinal permeability, and enrichment of beneficial microbial taxa. These findings indicate that potato RS represents a promising nutritional strategy for promoting intestinal health and productivity in commercial egg-laying systems.