Vibrio parahaemolyticus has been reported as a pathogenic bacterium that frequently attacks and causes high mortality in Pacific white shrimp (Litopenaeus vannamei). Treating diseases with synthetic antibiotics has an impact on antibiotic resistance, polluting the environment, and endangering consumer health. Therefore, alternative options are needed to control diseases in shrimp, for example, the use of natural ingredients with immunostimulant properties. This study aims to test the supplementation effect of Chlorella vulgaris flour in feed to improve growth, immune system and resistance to V. parahaemolyticus infection in juvenile of Pacific white shrimp. This study examined four treatments consisting of feed supplemented with 2%, 6%, 10%, and 14% C. vulgaris flour (Cv.2%, Cv.6%, Cv.10%, and Cv.14%) respectively, with three replications. Shrimp were reared and fed for 30 days with feed according to the treatment, and on the 31st day they were challenged with V. parahaemolyticus. The results showed that Cv.14% resulted in the highest absolute growth, recovery rate, and survival compared to the other three treatments and with the lowest prevalence of vibriosis disease. Furthermore, based on the hemolymph profiles, the Cv.14% treatment resulted a better system-enhancing response than the other treatments. This study shows that Cv.14% treatment is the best dose to improve growth performance and the disease resistance to prevent V. parahaemolyticus infection in Pacific white shrimp.
