Title: Effect of dietary protein levels on growth and protein utilization in juvenile Arctic char (Salvelinus alpinus)

A six-week trial was conducted with juvenile Arctic char reared in 20 l flow-through buckets to study the effect of dietary protein level on protein retention in the fish. At the end of the study, growth parameters and conversion efficiencies were all sensitive to the increased dietary protein levels in feed. Specific growth rate (SGR%) and live weight gain (LWG%), increased with increased dietary protein levels. The highest SGR (2.75±0.05) and LWG (285.41±9.62) were recorded from fish fed 39.89% Crude Protein (CP). The SGR and LWG values recorded from fish fed 29.30% CP performed remarkably well. Statistically, the FCR values recorded were not significantly different from each other except the value recorded at CP level 30.61% (1.78), but it was not different from that at CP level 29.91% (1.71). The body protein content increased with increased dietary protein content. The highest body protein content was recorded at CP level 39.89%. There were generally no significant differences in body protein content among the other feeds. Protein efficiency ratio (PER) and protein productive value (PPV) were not different among treatments except at CP level 29.31%. Dietary protein level in feed was found to be directly proportional to growth rate but inversely proportional to PPV and PER.