NUTRITIVE-VALUE OF WHITE LUPIN (LUPINUS-ALBUS VAR LUTOP) FED TO RAINBOW-TROUT (ONCORHYNCHUS-MYKISS) - EFFECTS OF EXTRUSION-COOKING

Two experiments were conducted in rainbow trout (Oncorhynchus mykiss) to assess the nutritional value of diets containing crude (LC) or extruded at 120-degrees-C (LE1) and 145-degrees-C (LE2) lupin var ''Lutop'' as a partial protein source. In the first experiment, the apparent digestibility coefficient (ADC) of diets with 20 and 30% lupin was measured. In a second trial, the effects of diet containing 20% crude and extruded lupin on growth performance of trout were analyzed. It was found that the ADC of dry matter, proteins and lipids decreased with the incorporation of 20% crude lupin. The extrusion-cooking process increased the digestive utilization of nutrients, especially the nitrogen-free extract. After 83 d of feeding, decreased growth performance was observed in trout fed on LC diet. Those fed diets LE1 or LE2 showed increased growth, food intake, food efficiency and protein retention, attributed to the disappearance of antinutritional factors In extruded lupin.