NONESSENTIAL AMINO-ACID SOURCES IN CRYSTALLINE AMINO-ACID DIETS FOR TROUT (ONCORHYNCHUS-MYKISS)

A study was conducted over a 84-day period to evaluate glycine, L-glut amic acid and L-glutamine as sources of non-essential amino acids (NEA A) in dietary 'protein' consisting of crystalline amino acids only. Th e study was performed with a total of 1200 rainbow trout fingerlings ( Oncorhynchus mykiss) of 48 g mean body mass. The addition of non-essen tial amino acids (NEAA) to essential amino acids (EAA) evidently impro ved growth and feed efficiency: glutamine was superior to glycine and glycine superior to glutamic acid. However, the best results in growth were obtained by adding a mixture of all three NEAA. The improvement of trout performance be glutamine may hypothetically be traced back to a better amino acid absorption capacity by a less acidic intestinal m ilieu. In consequence, the optimal EAA to NEAA ratio may have to be re defined.