Effect of three probiotic Bacillus strains supplemented feeds on growth, carcass composition and blood parameters of Clarias magur (Hamilton)

Abstract

ABSTRACT Lysinibacillus sphaericus PKA17, Bacillus cereus PKA18 and Bacillus thuringiensis PKA19, isolated from the intestine of adult indigenous magur (Clarias magur), were evaluated as putative probiotics for the cultivation of C. magur fingerlings. A total of 180 magur fingerlings (average weight 4.01 ± 0.01 g) were randomly distributed into four dietary groups in triplicate. The fingerlings were cultivated for 120 days into continuous-flow experimental rectangular cemented tanks (195 × 105 × 90 cm3; 1600 l; 5 cm bottom mud). Probiotics were mixed in feed (PT1: 2 × 106 L. sphaericus PKA17 cells; PT2: 2 × 106 B. cereus PKA18 cells; PT3: 2 × 106 B. thuringiensis PKA19 cfu/kg of basal feed where, PT = Probiotic treated) and fed to different dietary groups of fish. However, the control feed comprises of basal ingredients, and was not supplemented with any bacterial isolate. Fish carcass composition revealed significantly (p < 0.05) higher amounts of carbohydrate (2.8 ± 0.06 g kg−1), iron (2.21 ± 0.01 mg 100 g−1), fat-soluble vitamins and amino acid in fish fed PT1 than other groups. Fish fed PT1 feed also displayed a considerably higher protein efficiency ratio (2.05 ± 0.01) and lower feed conversion ratio (1.23 ± 0.01). Higher carcass protein content (164.9 ± 0.23 g kg−1) was observed in fish fed PT3 feed followed by PT1 and PT2. Fish fed probiotic-supplemented feed (PT1, PT2, and PT3) showed higher amounts of high-density lipoprotein and calcium than the control-fed fish. High survivability was observed in fish fed probiotic-feed compared to the control group. The results suggest that feed (PT1, PT2, PT3) incorporated with these probiotics might enhance the growth of C. magur in captivity, which may promote the cultivation of this endangered species.