Effect of the dietary coneflower (Echinacea purpurea) powder on growth, survival, immune-antioxidant system, and resistance to environmental stresses in Pacific white shrimp Litopenaeus vannamei

Plant-derived feed additives are increasingly used to enhance growth performance, immune competence, and stress tolerance in shrimp aquaculture. This study evaluated the effects of dietary Echinacea purpurea powder (EPP) on growth performance, immune–antioxidant responses, immune-related gene expression, and resistance to environmental stress in Pacific white shrimp ( Litopenaeus vannamei ). Shrimp were fed four experimental diets containing 0% (control), 2.5%, 5%, or 10% EPP for 68 days. Shrimp fed the 5% and 10% EPP diets showed significantly higher weight gain and lower feed conversion ratios compared with the control, while survival did not differ among treatments. Dietary EPP significantly enhanced antioxidant enzyme activities (superoxide dismutase and glutathione peroxidase), lysozyme activity, hemolymph protein and albumin concentrations, total hemocytes, and the proportions of semi-granular and large granular hemocytes. The most consistent improvements of these parameters was observed at the 5% inclusion level. In addition, EPP supplementation upregulated the expression of immune-related genes (α2-M, integrin β, PX, LGBP, and proPO1 ) in the hepatopancreas, particularly at 2.5% and 5% EPP. Shrimp fed EPP diets also exhibited significantly higher survival following exposure to low and high pH and cold temperature stress compared with the control. These results indicate that dietary EPP enhances growth efficiency, immune function, and stress resistance in L. vannamei , and that a dietary inclusion level of 5% EPP appears to be the most effective and practical dose under the conditions of this study.