Effects of dietary excesses of branched-chain amino acids on the metabolism and tissue composition of lake trout (Salvelinus namaycush)

1. Excesses of either leucine, isoleucine or valine were fed in separate experiments to determine if the branched-chain amino acid antagonism reported in other animals occur in trout (Salvelinus namaycush).

2. Parameters measured include growth rate, feed utilization efficiency, plasma and muscle-free amino acids, carcass composition and branched-chain amino acid aminotransferase.

3. Dietary excesses of leucine or isoleucine caused an increase in the valine requirement.

4. The inability of leucine and isoleucine supplementations to ameliorate the effects of excess dietary valine are interpreted as a valine toxicity rather than an antagonism.