SYNBIOTIC DIETARY SUPPLEMENTATION  ENHANCE THE IMMUNE RESPONSE AND GROWTH PERFORMANCE OF PACIFIC WHITE SHRIMP, Litopenaeus vannamei  AGAINST WHITE SPOT SYNDROME VIRUS INFECTION    

White spot syndrome virus (WSSV) is one of devastating shrimp pathogenic which causes up to 70-90% mortality in commercial shrimp farming. This study was aimed to evaluate the effectiveness of synbiotic microcapsule (mixture of Bacillus sp. and mannan oligosaccharide) as feed supplementation on the immune response and growth performance of WSSV-infected shrimp. Pacific white shrimps (average body weight of 4.411 ± 0.395 g shrimp^-1) were fed by pellet supplemented by synbiotic microcapsule at different dosages for 30 days. Different dosages of treatment were designated as 0.5% (M1), 1% (M2), 2% (M3) (w/w) and without feeding supplementation, included negative (KN) and positive (KP) controls. The synbiotic was encapsulated by spray drying method. The challenge test was conducted at 31^st day by intramuscular injection of WSSV filtrate (10⁴ copy mL^-1). The results showed that the specific growth rate (SGR) of M1 and M2 were higher (p<0.05) than controls. Yet, the feed conversion ratio (FCR) were lower (p<0.05) than controls. The final survival rate of shrimps with dietary supplementation were higher (p<0.05) than controls (Table 1). In addition, treatments of M2 and M3 showed higher (p<0.05) values of total hemocytes count (THC), pro phenoloxydase (proPO) and respiratory burst (RB) activities (Table 2) compared to KP. Based on the results; 1% of dietary supplementation showed its capability to enhance shrimp immune response and growth performance against WSSV-infection.