The amino acid profiles in developing eggs and larvae of the freshwater Percichthyid fishes, trout cod, Maccullochella macquariensis and Murray cod, Maccullochella peelii peelii

Results on changes in the total amino acids (protein bound + free) and the free amino acids (FAA) in relation to development, from egg (unfertilised a nd/or fertilised) to yolk-sac resorbed larva, before first feeding, in two Percichthyid fish, trout cod, Maccullochella macquariensis and Murray cod, Maccullochella peelii peelii, which lay demersal, adhesive eggs, are presen ted. Throughout development, the FAA accounted for only a small proportion (0.19 % in fertilised eggs of both species) of the total amino acid pool. N ine essential amino acids (EAA) and eight non-essential amino acids (NEAA) were quantified in the amino acid pool at all stages of development. In bot h species, the total amino acid content decreased during the transformation (at 20 +/- 1 degrees C) from newly hatched larva to yolk-sac resorbed larv a. Overall, the changes in the TEAA and TNEAA reflected that of the amino a cid pool. In trout cod, all but one EAA (lysine) and two NEAA (cysteine and glycine) decreased with ontogeny, from fertilised egg to yolk-sac resorbed larva. In Murray cod, however, the exceptions to the general decline were two NEAA (aspartic acid and glycine). In contrast, the FAA increased with d evelopment, the changes being reflected in both FEAA and FNEAA. Qualitative ly, the predominant free amino acids in trout cod and Murray cod eggs were alanine, lysine, leucine and serine. Because the egg protein and the total amino acid contents declined with development, it is concluded that the rat e of breakdown of yolk protein was higher than the anabolic and catabolic p rocesses during embryogenesis. Data also suggest that in freshwater fish FA A are an unlikely primary energy substrate during embryogenesis. (C) 1999 I fremer/Cnrs/Inra/Ird/Cemagref/Editions scientifiques et medicales Elsevier SAS.