Effects of polyphenol rich sugarcane extract on growth performance, survival, immune responses, and resistance to Vibrio parahaemolyticus and white spot syndrome virus infections of Pacific white shrimp, Litopenaeus vannamei

Polyphenol-rich sugarcane extract (PRSE) is a product of sugarcane obtained from the sugar refinery industry and can potentially be used as a feed additive in farmed animals. The purposes of the current study were to evaluate the effects of PRSE on growth performance, survival, immune responses, and resistance to Vibrio parahaemolyticus and white spot syndrome virus (WSSV) infections of Pacific white shrimp, (Litopenaeus vannamei). In Experiment 1, the postlarvae were randomly divided into five groups (8 replicates/group and 80 shrimp/tank) and fed commercial feeds supplemented with PRSE at the rate of 0 (control), 0.2, 0.4, 0.6, and 0.8% of the diets four times/day for 60 days to evaluate the body weight, survival rate, and immune function. In Experiment 2, the juvenile shrimp from Experiment 1 were randomly redistributed into six groups (four treatment groups as in Experiment 1, positive control, and negative control with 3 replicates/group and 30 shrimp/tank) and challenged with either V. parahaemolyticus or WSSV via immersion (105 colony-forming units/mL) and oral (feeding with infected tissues) routes, respectively, to evaluate disease resistance. Our results demonstrated that shrimp body weight for the 0.8% PRSE group was significantly greater than the other groups, and those fed 0.4%-0.8% PRSE demonstrated a significant improvement in survival, total hemocyte count, phagocytic activity, phenoloxidase activity, and superoxide dismutase activity compared with the controls. On day 7 following the V. parahaemolyticus challenges, the survival rates of the 0.4%-0.8% PRSE-fed shrimp (70%-73%) were significantly greater than the control counterpart (46%). However, shrimp challenged with WSSV suffered severe mortality regardless of the treatment groups, but those treated with 0.4%-0.8% PRSE showed delayed mortality. In conclusion, results suggested that dietary PRSE supplemented at 0.4%-0.8% diets were beneficial for improving overall health and disease resistance in shrimp culture.