1Department of Aquatic Biosciences, Tokyo University of Fisheries, Tokyo 108-8477, 2Fisheries Research Station, Faculty of Agriculture, Kyoto University, Kyoto 625-0086, 3National Research Institute of Fisheries Science, Kanagawa 236-8648, Japan
This experiment was conducted to investigate the effects of taurine on growth, taurine levels in whole body and sulfur amino acids metabolism of juvenile Japanese flounder Paralichthys olivaceus. In the control diet, brown fish meal was used as the sole protein source to provide 55% protein. Diets 2, 3 and 4 were supplemented with graded levels of essential amino acid (EAA) mixture, non-essential amino acid (NEAA) mixture and taurine, respectively. Diets 5, 6 and 7 were supplemented with EAA mixture, NEAA mixture, and taurine, respectively. These diets were fed to the juvenile Japanese flounder with an initial mean body weight of 0.15g for 5 weeks.
The fish fed a taurine supplemented diet showed significantly better (p<0.05) growth than those fed the control diet and diets 5 and 6. These results clearly indicated that the supplemented taurine in the diet improves the growth of juvenile Japanese flounder.
A clear relationship was noted between the level of taurine accumulated in the whole body of fish and the taurine level in the diet. But the taurine accumulated levels in the whole body was not affected by contents of over 20mg/g taurine in the diet. On the other hand, fish fed the control diet and diets 5 and 6 showed a higher increase in cystathionine contents in the whole body. These results suggest that the taurine content in diet affects the surfur amino acids metabolism of juvenile Japanese flounder, and the taurine requirement may be 15-20mg/g in diet.