Dietary Wedelia chinensis extract enhances growth performance and strengthens innate immunity of whiteleg shrimp (Penaeus vannamei) against Vibrio parahaemolyticus

This study evaluated the effects of dietary top-coating supplementation with Wedelia chinensis extract on growth performance, innate immune responses, and disease resistance in whiteleg shrimp (Penaeus vannamei) challenged with Vibrio parahaemolyticus. Shrimp were fed a basal diet top-coated with W. chinensis extract at inclusion levels of 31.25, 312.5, or 625 mg kg^-1 feed using an intermittent feeding protocol over a 21-day period, while a control group received the unsupplemented basal diet. Growth performance indicators, including weight gain and feed conversion ratio, were significantly improved in shrimp fed extract-supplemented diets, with the most pronounced effects observed at the intermediate inclusion level. In addition, many key innate immune parameters, including total hemocyte count, phagocytic activity, phenoloxidase, lysozyme, and superoxide dismutase activities, were significantly elevated compared with the control group. Following pathogen challenge, shrimp fed W. chinensis–supplemented diets exhibited significantly reduced mortality, indicating enhanced resistance to V. parahaemolyticus. Overall, the results suggest that dietary supplementation with W. chinensis extract can beneficially modulate growth performance and innate immune responses in whiteleg shrimp. Further studies are warranted to elucidate the underlying mechanisms, identify active compounds, and evaluate long-term efficacy under commercial farming conditions.