The effect of taurine supplementation to a plant-based diet for barramundi (Lates calcarifer) with varying methionine content

The effect of variable taurine inclusion (Tau) (1g/kg DM to 15g/kg DM) in the diet of juvenile barramundi (Lates calcarifer) on growth and nutrient utilization was investigated at three levels of dietary methionine (Met) supplementation. Diets were fed to juvenile barramundi (starting weight: 26.8g) twice daily under a restricted pair-fed regime for a period of 42days. No significant effect of dietary Tau supply on growth or nutrient utilization was observed at any level of Met inclusion. Numerical variations suggested a positive effect of Tau provision at the mid-level of supplementation (6-8g/kg DM). The best-fit response model (5-SKM), fitted to the percentage body weight gain data of fish fed diets with an adequate level of Met, suggested a relatively weak pattern of response (R-2 = 0.183) and predicted a Tau requirement of 5.47g/kg DM (9.64 g/kg CP) similar to that reported for several other species. It was concluded that taurine appears to be conditionally essential to barramundi, whereby provision in the diet when sulphur amino acid supply is insufficient to meet biosynthetic demands may be beneficial, but that the predicted requirement is likely reasonably accurate for use as a minimum level of inclusion.