EFFECTS OF DIETARY TAURINE AND RELATED AMINO ACIDS ON GROWTH PERFORMANCE AND TAURINE TRANSPORTER (TAUT) MRNA EXPRESSION OF JUVENILE TURBOT (SCOPHTHALMUS MAXIMUS L.)

A 10-week feeding experiment in indoor flowing-through water system was conducted to evaluate the effects of taurine, methionine and cysteine in diets on growth performance and taurine transporter (TauT) mRNA expression of juvenile turbot (Scophthalmus maximus L.)initial weight:(7.90±0.07) g. The basal diet was supplemented with 0, 1%, 2% taurine, 0.5% methionine and 0.5% cysteine (Control T-0, T-1, T-2, M-0.5 and C-0.5, respectively) to formulate five isonitrogenous and isolipidic diets. The results showed that the specific growth rate (SGR) and feed efficiency (FE) of T-1 and T-2 group were significantly higher than that of the control group (P < 0.05), and the visceral indexes (VSI) of T-1 and T-2 group was significantly lower than that of the control group (P < 0.05). Compared with T-0 group, the SGR and FE of M-0.5 group improved (P>0.05), and VSI decreased significantly (P < 0.05), while condition factors (CF) increased significantly (P < 0.05). Compared with T-0 group, the SGR of C-0.5 group decreased signifi-cantly (P < 0.05), and no significant differences in FE, VSI and CF were observed (P>0.05) between the two groups. T-1 and T-2 group had significantly lower TauT mRNA relative expression (P < 0.05) in liver, brain and eye tissues than those in T-0 group, and the TauT mRNA relative expression in liver, brain and eye tissues decreased significantly (P < 0.05) with increasing dietary taurine level. On the contrary, the TauT mRNA relative expression in liver, brain and eye tissues of M-0.5 group was significantly higher (P < 0.05) than those in T-0, T-1 and T-2 groups. C-0.5 group had a significantly higher TauT mRNA relative expression (P < 0.05) in liver, brain and eye than those in T-0, T-1 and T-2 groups, but no significant differences (P>0.05) were found when compared with M-0.5 group. In conclusion, 0.48%, 1.06% taurine in diets could promote growth performance of juvenile turbot under these experimental conditions. The TauT mRNA expression in juvenile turbot may be affected by dietary sulfur-containing amino acids such as taurine, methionine and cysteine.