The combined impact of xylo-oligosaccharides and gamma-irradiated Astragalus polysaccharides on growth performance and intestinal mucosal barrier function of broilers

This study was conducted to investigate the individual and combined effects of xylo-oligosaccharides (XOS) and gamma-irradiated Astragalus polysaccharides (IAPS) on the growth performance and intestinal mucosal barrier function of broiler chickens. A total of 240 1-day-old Ross-308 chicks were allocated into 5 groups for 21 d: control group (basal diet), antibiotic growth promoter (AGP) group (basal diet supplemented with 50 mg/kg chlortetracycline), XOS group (basal diet supplemented with 100 mg/kg XOS), IAPS group (basal diet supplemented with 600 mg/kg IAPS), and XOS + IAPS group (basal diet supplemented with 100 mg/kg XOS and 600 mg/kg IAPS). The results showed that birds in the XOS + IAPS group showed higher ADG and lower feed-to-gain ratio than those in the control group (P < 0.05). The XOS, IAPS, and XOS + IASP treatments significantly increased villus height (VH) of all intestine segments, jejunal goblet cell numbers, and VH–to–crypt depth ratio (VH/CD) of broilers than those of the control group (P < 0.05). Birds in the XOS + IAPS group had higher jejunal VH/CD ratio and goblet cell numbers than those from the XOS or IAPS groups (P < 0.05). In addition, there was a synergy effect between XOS and IAPS on increasing duodenal goblet cell numbers and improving ileal morphology (higher VH and VH/CD ratio) (P < 0.05). The XOS, IAPS and XOS + IAPS treatments increased the mRNA expression of zonula occludens-1 and occludin of the jejunum as compared with the control group (P < 0.05). Simultaneously, birds in the XOS + IAPS group showed lower plasma D-lactic acid concentration and higher mRNA expression of claudin-1, claudin-3, and occludin in the jejunum than those in the control or IAPS groups (P < 0.05). Moreover, there was no significant difference in growth performance, intestinal morphology, and intestinal barrier function of broilers between the AGP and XOS + IAPS groups. In conclusion, the combination of XOS and IAPS had a better potential as chlortetracycline substitute for improving the growth performance, intestinal morphology, and intestinal barrier function of broilers.