Effects of ANT, APS, and GPS on mRNA expression of occludin (A), claudin-1 (B), zonula occludens-1(ZO-1) (C), and mucin-2(MUC2)(D) in small intestine. Data are means ± SEM, n = 6. Means with different letters indicate significant difference (P < 0.05). Abbreviations: ANT, basal diet supplemented with 500 mg/kg terramycin calcium; APS, basal diet supplemented with 300 mg/kg Astragalus membranaceus polysaccharides; CON, control group with basal diet; GPS, basal diet supplemented with 150 mg/kg Glycyrrhiza uralensis polysaccharides.