Dietary Echinacea purpurea polysaccharide supplementation improves antioxidative status, intestinal immune, and structure of cecal microbiota in Mahuang chickens.

Echinacea purpurea polysaccharide (EPP), a key bioactive constituent of the natural immunostimulant E. purpurea, shows potential as a poultry feed additive. This study evaluated EPP's impact on growth performance, serum biochemistry indices, organ index, antioxidant capacity, immunity, intestinal health, and microbiota in Mahuang chickens. A total of 180 one-day-old Mahuang chicks (initial average body weight 39.10 ± 0.51 g) were randomly divided into six groups (six replicates, five chicks per replicate): a basal diet with 0 (CON), 0.1 g/kg levamisole hydrochloride (LMS), 100 mg/kg EPP (EPP100), 200 mg/kg EPP (EPP200), 400 mg/kg EPP (EPP400), and 800 mg/kg EPP (EPP800) for 42 days. The results showed that EPP did not affect serum biochemical indices and organ index, but significantly improved growth performance by increasing body weight gain (d 21) (p < 0.05). Additionally, EPP improved intestinal (duodenum, jejunum, and ileum) morphology by increasing villus height and villus height-to-crypt depth ratio, and decreasing crypt depth (d 21 and d 42) (p < 0.05). Com-pared to the CON and LMS groups, EPP significantly increased superoxide dismutase activity (p = 0.011) and total antioxidant capacity activity (p = 0.001) (d 21), elevated the levels of immunoglobulin (Ig) M (p < 0.001) and secretory IgA (p = 0.038) (d 21), and upregulated intestinal barrier-related genes (d 21 and d 42) (p < 0.05). 16S rRNA gene sequencing revealed that EPP treatment increased the Bacteroidetes/Firmicutes ratio. EPP also elevated the relative abundances of Bacteroides, Lactobacillus, Ruminococcus, Butyricicoccus, Oscillospira, and Akkermansia, while decreasing the relative abundance of Streptococcus (p < 0.05). Overall, the EPP groups outperformed the CON and LMS groups, with the high-dose groups (EPP400, EPP800) showing superior effects to the low-dose groups (EPP100, EPP200). In summary, this study confirmed that supplementing with EPP could boost growth performance, antioxidant capacity, immunity, intestinal barrier function, and cecal microbial community in Mahuang chickens without adverse effects, and the 400-800 mg/kg EPP appears to be optimal. This highlights the potential of EPP as a safe and effective alternative to synthetic immunostimulants in poultry production.