Studies on the use of branced chain amino acids in the diet for salmonids

Rainbow trout (Salmo gairdnerii) and Atlantic salmon (Salmo salar) were fed low protein diets, with or without supplementation by mixtures of branched chain amino acids. Groups receiving standard high protein diets were included as controls. In both species of fish the high protein groups gained weight more rapidly than the experimental low protein groups, but the differences were not great. No consistent improvement of growth was observed when branched chain amino acids were given as a supplement to the low protein diets. No differences were found between groups in the muscle tissues activities of the branched chain amino acid metabolizing enzymes, leucine: a-keto glutarate aminotransferase and branched chain a-keto acid dehydrogenase, in either species. These enzyme activities were lower in salmon muscle than in trout muscle.