Effect of Dietary Supplementation of Bacillus spp. on Growth Performance, and Resistance of Pacific White Shrimp (Litopenaeus vannamei) to Acute Hepatopancreatic Necrosis Disease

This study was conducted to investigate effect of dietary supplementation of three Bacillus spp. on disease resistance of L. vannamei against Vibrio parahaemolyticus, a main causative pathogen for acute hepatopancreatic necrosis disease (AHPND), and growth performance and feed efficiency. Four diets were prepared by supplementing powder forms of Bacillus spp. (1 × 1010 CFU/g) with a combination at 0.2% (BS, B. subtilis only), 0.4% (BS/BP, a mixture of B. subtilis and B. pumilus), and 0.6% (BS/BP/BL, a mixture of B. subtilis, B. pumilus and B. licheniformis) into a control diet (no supplement). Quadruplicate groups of shrimp (average body weight, 0.51 g) per each diet were hand-fed the diets for 33 days. Shrimp fed the BS diet had significantly higher growth performance than those fed the control diet or other diets (BS/BP and BS/BP/BL) (P<0.05). After the feeding trial, the shrimp were challenged with V. parahaemolyticus through an immersion method at a concentration of 2 × 105 CFU/ml water for 193 h. The shrimp groups fed the Bacillus supplemented diets showed significantly increased (P