Growth performance,nutrient digestibility and digestive enzyme activity in Asian seabass,Lates calcarifer juveniles fed diets supplemented with cellulolytic and amylolytic gut bacteria isolated from brackishwater fish

Asian seabass, Lates calcarifer juveniles were fed for 30 days to evaluate the efficacy of cellulolytic (Bacillus sp. DDKRC1.) and amylolytic (Bacillus subtilis DDKRC5.) bacteria supplemented diets. Four experimental groups were maintained in triplicate of which group I was the control group and received no bacterial supplementation. Groups II, III and IV were fed diet supplemented with B. subtilis DDKRC5. (14.25 × 10⁷ CFU/mL), Bacillus sp. DDKRC1. (2.94 × 10⁷ CFU/mL) and mixture of both the microbes (1:1 ratio), respectively, @ 1% (v/w). After 30 days of feeding, fish reared as group IV showed significantly higher (P < 0.01) weight gain (141.42%), survival (91.50%), protein efficiency ratio (1.18) and significantly lower (P < 0.01) FCR (2.15) than that of other groups. Nutrient digestibility parameters were significantly (P < 0.01) higher in group IV followed by groups III, II and I. Digestive cellulase, amylase and protease activities in the gastrointestinal tract were also significantly (P < 0.01) higher in group IV. Amylolytic and cellulolytic microbial count in the gastrointestinal (GI) tract were significantly (P < 0.01) higher in groups II, III and IV as compared with that of control. It can be concluded that feed supplemented with mixture of B. subtilis DDKRC5. and Bacillus sp. DDKRC1. showed better performance in Asian seabass juveniles.