N-acetylated chito-oligosaccharides and xylanase improve intestinal health and production performance in laying hens

Synergistic feed additives that target the gut-immune axis offer a promising strategy to enhance health, nutrient utilization, and productivity. N-acetylated chito-oligosaccharides (NACOS) provide stimbiotic, antimicrobial, and immunomodulatory benefits, while xylanase improves non-starch polysaccharide degradation, nutrient availability, and microbial fermentation. This study evaluated a novel dual-action strategy combining NACOS, xylanase, or their combination (CXNRGY) on production performance, nutrient utilization, jejunal histomorphology, systemic immune status, and the cecal microbial community in laying hens. Forty HiSex White laying hens were randomly assigned to four dietary groups and fed either a control diet (CD) or the CD supplemented with NACOS (50 g/t), Xylanase (45,000 U/kg), or CXNRGY at the same respective doses. Dietary supplementation improved production metrics: egg weight was highest in the CXNRGY group compared with control and NACOS (P < 0.001), while egg mass increased in Xylanase, NACOS and CXNRGY groups compared to control in the second phase (P < 0.001). Xylanase and CXNRGY achieved the lowest FCR compared with NACOS and the control group. Haugh unit and albumen height were elevated in NACOS and Xylanase treatments (P < 0.05), whereas CXNRGY maximized shell thickness and breaking strength (P < 0.001). Nutrient utilization of crude fat, organic matter, and apparent metabolizable energy (AME) was significantly improved by NACOS, while Xylanase and CXNRGY further enhanced fiber and protein utilization. NACOS produced the greatest improvements in jejunal morphology (P < 0.05) and, along with Xylanase and CXNRGY, reduced serum IL-1α, TNF-α, and IL-10 (P < 0.05), while IL-1β and IL-6 were unaffected (P > 0.05). Notably, CXNRGY altered the cecal microbiota by increasing the relative abundance of Lachnospiraceae, Ruminococcaceae, Subdoligranulum, Prevotellaceae and Clostridia, while decreasing Bacteroidaceae and Negativicutes, indicating a synergistic effect on microbial community structure. Xylanase enhances nutrient utilization and prebiotic availability, while NACOS strengthens gut barrier integrity and modulates immune responses. These results indicate that combining NACOS with xylanase provides a synergistic, antibiotic-free nutritional strategy that enhances gut health, immunity, egg quality, and overall performance in laying hens.