Mixed Fungal Polysaccharides Enhance Intestinal Health, Antioxidant Capacity, and Microbiota Diversity in Broiler Chickens

Abstract

Poultry production faces escalating challenges from intensive farming practices, where stressors disrupt intestinal integrity, microbiota balance, and antioxidant defenses, leading to economic losses. Although antibiotics have historically mitigated such issues, growing restrictions due to antimicrobial resistance necessitate natural alternatives. Fungal polysaccharides (FP), notably lentinan (LNT) from Lentinula edodes and polysaccharide from Ganoderma lucidum (GLP), are promising candidates owing to their immunomodulatory, antioxidant, and prebiotic properties. However, existing research focuses predominantly on individual FP, neglecting potential synergies in blended formulations. We hypothesized that mixed FP synergistically enhance intestinal health by simultaneously improving nutrient absorption, activating antioxidant pathways, and stabilizing microbial ecosystems. To investigate, 240 one-day-old Arbor Acres male broilers were randomly assigned to control (0 mg/kg FP) and treatment groups receiving 200, 400, or 600 mg/kg mixed FP (1:1 ratio of GLP and LNT). On day 42, intestinal segments were collected for morphological analysis, antioxidant enzyme activities, gene expression, and cecal microbiota composition. Results showed that 400 mg/kg FP significantly increased villus height and VH/CD ratio across all intestinal segments while reducing crypt depth, indicating enhanced nutrient absorption. Antioxidant enzyme activities (T-AOC, T-SOD, GSH-Px) were elevated, and mRNA expression of HO-1, NQO1, CAT, and Nrf2 was upregulated, with Keap1 downregulated, suggesting activation of the Keap1-Nrf2 pathway. Microbiota analysis revealed increased alpha diversity (Shannon and Simpson indices) and altered composition, with elevated abundances of beneficial genera such as Butyricimonas and Alistipes, and increased Verrucomicrobiota phylum. These findings demonstrate that mixed FP supplementation at 400 mg/kg improves intestinal health, antioxidant capacity, and microbiota diversity in broilers, offering a natural alternative to antibiotics.

1. Introduction

Poultry production faces escalating challenges from intensive farming practices, where stressors, including high stocking density, pathogen exposure, and dietary fluctuations, disrupt intestinal integrity, microbiota balance, and antioxidant defenses [1]. These disruptions impair nutrient absorption, growth performance, and immune function, leading to significant economic losses [2]. Although antibiotics have historically mitigated such issues, growing restrictions due to antimicrobial resistance necessitate natural alternatives [1]. Fungal polysaccharides (FP)—notably lentinan (LNT) from Lentinula edodes and polysaccharide from Ganoderma lucidum (GLP)—are promising candidates owing to their immunomodulatory, antioxidant, and prebiotic properties [3]. However, existing research focuses predominantly on individual FP, neglecting potential synergies in blended formulations.

Structurally, LNT (β-(1→3)-D-glucan backbone) enhances rumen volatile fatty acid production and fiber degradation [4], whereas GLP (heterogeneous α/β-glycans) potently activates the Nrf2/HO-1 antioxidant pathway and modulates Th1/Th2 immunity [5]. These divergent mechanisms imply complementary effects when combined. In our previous experiments on broiler feeding, we reported that a combination of GLP (68.32% polysaccharide content, composed of mannose, glucose, arabinose, rhamnose, and galactose at a molar ratio of 1.00:16.37:18.82:1.42:17.42) and LNT (76.52% polysaccharide content, composed of mannose, galacturonic acid, arabinose, galactose, glucose, and rhamnose at a molar ratio of 1.00:15.22:8.23:2.05:1.78:4.26) at a 1:1 ratio maximally promoted broiler growth (unpublished data), but their impacts on intestinal morphology, antioxidant signaling, and the microbiota remain uncharacterized. We therefore hypothesize that mixed FP synergistically may enhance intestinal health by simultaneously improving nutrient absorption, activating antioxidant pathways, and stabilizing microbial ecosystems.