Effect of dietary vitamin B 6 supplementation on growth and intestinal microflora of juvenile golden pompano ( Trachinotus ovatus )

In order to investigate the dietary vitamin B 6 (VB 6 ) requirement for juvenile golden pompano, an experiment of six different diets with six dietary VB 6 levels (0, 3.75, 7.47, 10.6, 13.7 and 18.5 mg/kg) was conducted. The results indicated that the content of dietary VB 6 significantly increased weight gain rate (WGR), specific growth rate (SGR) and feed conversion ratio (FCR; p  < 0.05). Golden pompano fed diet containing 7.47 mg/kg VB 6 achieved the maximum ALT, AST, GPx, hepatic VB 6 concentrations as well as the minimum MDA, however, the ALT, AST, GPx and hepatic VB 6 concentrations decreased while MDA increased with a further increase in dieatry VB 6 . The highest values of GR and POD occurred at the 10.6 and 13.7 mg/kg dietary VB 6 ( p  < 0.05) respectively. A diet supplemented with 7.47 mg/kg VB 6 increased intestinal Na + , K + ‐ATPase, Chymotrypsin, γ‐glutamyl transpeptidase, creatine kinase and amylase activities ( p  < 0.05). The relative abundance of Tenericutes and Bacteroidetes decreased while Proteobacteria and Firmicutes improved with an increase in dietary VB 6 levels up to 7.47 mg/kg. Quadratic regression analysis on WGR, hepatic VB 6 concentrations, AST and ALT indicated that the optimum dietary VB 6 levels for juvenile golden pompano were 8.84–9.28 mg/kg.