Lysine requirement of juvenile Japanese flounder Paralichthys olivaceus and juvenile red sea bream Pagrus major

The lysine requirement of juvenile Japanese flounder (3.0 g initial weight) and red sea bream (1.7 g initial weight) was estimated by feeding six semi-moist diets (45-48% crude protein on dry basis) containing graded levels of lysine hydrogen chloride in replacement of sodium glutamate. Most of the amino acids in the diets were provided by zein, fish meal and gelatin. In addition, free amino acids were added to ensure that the requirements for the essential amino acids, other than lysine, were met. Specific growth rate, feed efficiency, and nitrogen retention data were analyzed by non-linear regression using the broken-line model to obtain the lysine requirement estimates for Japanese flounder of 3.3, 4.2 and 4.6% of dietary protein, respectively, and 3.6, 4.3, and 4.4% of dietary protein for red sea bream. Estimates of the requirements for the other essential amino acids were made based on A/E ratios of the whole-body amino acid profile. (C) 1998 Elsevier Science B.V.