Estimation of the dietary biotin requirement of juvenile hybrid tilapia, Oreochromis niloticus×O. aureus
A growth study was conducted to determine the dietary biotin requirement of juvenile hybrid tilapia, Oreochromis niloticus×O. aureus. Purified diets with 8 levels (0, 0.05, 0.1, 0.3, 0.6, 1.0, 3.0, 5.0 mg/kg) of supplemental biotin were fed to tilapia (mean weight 0.98±0.01 g) for 8 weeks. Each diet was fed to three replicate groups of fish. Results indicated that highest (P<0.05) weight gain was for fish fed the diet supplemented with 0.1 mg biotin/kg, followed by fish fed the diets with 0.05, 0.6, 1.0, 3.0 and 5.0 mg biotin/kg, and lowest in fish fed the unsupplemented control diet. Body biotin concentration in the fish was affected by dietary biotin. Increased body biotin concentration was observed as dietary biotin increased. Hepatic pyruvate carboxylase and acetyl CoA carboxylase activities were higher in fish fed the diets supplemented with biotin than in fish fed the control diet. Broken-line analysis of weight gain on levels of dietary biotin indicated that the dietary biotin requirement for maximal growth of tilapia is about 0.06 mg/kg diet.