Effects of Echinacea Purpurea Polysaccharides on Growth Performance, Serum Biochemistry, and Intestinal Health of Immunosuppressed Broilers

Echinacea polysaccharide (EPP) is one of the main active ingredients of Echinacea purpurea and has been shown to possess antioxidant, anti-inflammatory, and immune-enhancing activities. The study investigated the effects of supplementing the diet with different doses of EPP on immunosuppressed broilers. A total of 180 one-day-old healthy broilers were randomly assigned to six groups, each with six replicates of five birds. C (control) and CTX (cyclophosphamide) groups received basal diet, while LLEP, LEP, MEP, and HEP groups were supplemented with 100, 200, 400, and 800 mg/kg EPP. On day 7, group C was injected with saline for three consecutive days, whereas the remaining groups received cyclophosphamide (CTX, 80 mg/kg) to induce immunosuppression. Intestine, liver, and serum samples were collected on days 14 and 28 for analysis. The results showed that all EPP-supplemented groups exhibited improved growth performance compared to the CTX group, and the immune organ index increased. Specifically, the MEP group showed an improvement in jejunal morphology, and the LLEP and LEP groups improved ileal morphology. The EPP-added groups had improved ileal morphology The EPP-added group exhibited improved jejunal and ileal intestinal barriers, i.e., Occludin, Claudin1, Claudin2 and MUC2 at different time periods, as well as immune-related markers, at different time points. Furthermore, the MEP and HEP groups showed upregulated Nrf2 gene expressions in the jejunum and ileaum. EPP supplementation reduced MDA contents in serum, liver, and small intestine. The LLEP group effectively increased GSH-Px in serum and liver, while the MEP group effectively increased T-AOC in serum, liver, and small intestine. Meanwhile, compared to the CTX group, the MEP group showed increased ALB levels and all groups supplemented with EPP showed elevated TP levels. In conclusion, EPP ameliorated cyclophosphamide-induced immunosuppression in broilers, with the optimal effect observed at a supplementation level of 400 mg/kg (MEP group).