EFFECT OF DIETARY-LIPID LEVEL ON PROTEIN-UTILIZATION AND THE SIZE ANDPROXIMATE COMPOSITION OF BODY COMPARTMENTS OF COLOSSOMA-MACROPOMUM (CUVIER)

Juvenile Colossoma macropomum were fed ad libitum diets containing eit her 30% or 40% protein, while the dietary lipid level varied between 5 % and 20%. Growth and protein utilization efficiency increased with th e dietary lipid level, However, the economic feasibility of the additi on of extra dietary lipid to C. macropomum diets is questionable as fo r every extra gram of protein deposition it was necessary to replace 2 0-25 g of dietary carbohydrates by lipids. Moreover, increased dietary lipid levels resulted in increased lipid deposition, In C., macropomu m, feed uptake was regulated by the dietary protein level and unaffect ed by the dietary lipid level. Dissection of the body into head, visce ra and trunk revealed that 45-48% of the body lipids were stored in th e trunk, independent of diet composition. A positive relation between dietary and body protein level was confirmed ih this experiment, Howev er, the dissection of the body revealed that the body protein concentr ations in head + viscera and trunk are not changed significantly by th e dietary protein level, The higher protein contents of fish fed highe r-protein diets are due to an increase in the relative weight of the t runk (muscle) to the total body weight.