Yeast cell wall polysaccharides accelerates yet in-feed antibiotic delays intestinal development in early chickens via modulating Wnt/β-catenin pathway and intestinal microbiome in early chickens
Authors: Guo Fangshen , Qiao Jianing , Hu Zeqiong , Huang Jia , Bi Ruichen , Abbas Waseem , Xu Tiantian , Qiu Baoqin , Jalukar Sangita , Wang Zhong 
Published: October 2023

Background
Gut development during early life of chickens is important for nutrients digestion and absorption, growth, immune and defensive function of chickens at all ages. Continuous antibiotics exposure in early life can delay intestinal development and maturity, disrupt intestinal flora, compromise intestinal mucosal immunity and vaccine efficacy, increase disease susceptibility as well as increase the probability of the development of anti-microbial resistant pathogens. The use of non-antibiotics substances to promote intestinal development and maturity in early chickens has become increasingly important. This study investigated the impacts of supplemental yeast cell wall polysaccharide (YCWP) on the intestinal development of broilers compared with in-feed antibiotics bacitracin methylene disalicylate (BMD) and further explored its underlying action mechanism.
Methods
Ninety 1-day-old healthy male Arbor Acres broilers were randomly assigned to three groups containing control (basal diets), antibiotics-treated group (control diet + 50 mg/kg BMD) and YCWP-supplemented group (control diet + 100 mg YCWP /kg diet), respectively.
Results
Contrary to BMD group, YCWP increased villus height (VH) at the 42 days of age (d42), crypt depth (CD, d21), VH:CD (d21), villus surface area (d21 and d42), obviously increased ileal alkaline phosphatase (ALP, d21) and maltase activity as well as the population of acidic goblet cells and IgA-producing plasma cells in the ileum (P < 0.05). YCWP addition upregulated intestinal stem cell marker Leucine-rich repeat containing G protein-coupled receptor 5 (d21) and Wnt/β-catenin signal pathway related genes (Wnt3, d21; β-catenin, d21 and d42) expressions (P < 0.05), increased the expression of marker of proliferation Ki-67 (Mki67, d21) and barrier related genes (Mucin-2, Lysozyme, occludin, FABP-2) as well as innate immune cells markers major histocompatibility complex I (MHC I, d42; MHC II d21), clusters of differentiation 80 (CD80, d21) and CD83 (d42) relative to the BMD treatment (P < 0.05). Moreover, YCWP boosted toll-like receptors (TLR)-mediated innate immune signal pathway related genes (TLR-1/-2/-6, d21) mRNA levels compared with the BMD group (P < 0.05). However, the expressions of TLR-2/-6 and inducible nitric oxide synthase (iNOS, d42) were markedly downregulated by YCWP in the later life of chickens as compared to the BMD (P < 0.05). Cecum microbiome analysis displayed that YCWP addition obviously improved intestinal microbial structure and composition, as evidenced by increasing cecal microbial α- diversity and β-diversity (d21 and d42) and enriching the relative abundance of Fournierella (d21), Psychrobacter (d21), Ruminiclostridium (d21), Bacteroidetes (d42), Alistipes and Lactobacillus (d42, P < 0.05). While BMD expanded Escherichia_Shigella (d21) and Streptococcus (d21 and d42) relative abundances (P < 0.05). Correlational analysis showed that Fournierella, Psychrobacter and Ruminiclostridium relative abundance was positively related with gut development-related indexes (ALP and maltase activity, β-catenin, Mki67, goblet cells counts, MHC II, TLR-1/-2/-6, and IL-22, P < 0.05). Alistipes showed a positive correlation with the expressive levels of β-catenin and MHC II along with goblet cell numbers, but negatively with iNOS expression (P < 0.05). Lactobacillus was positively related with maltase activity, and Wnt3, β-catenin, Mucin-2, MHC I mRNA abundances and goblet cells counts (P < 0.05).
Conclusion
Supplemental YCWP promoted yet antibiotics BMD delayed intestine development through modulating Wnt/β-catenin pathway and intestinal microbiome in early chickens