Evaluation of the nutritional value of processed lupin meal (Lupinus albus) with exogenous enzymes, as feed ingredient in European sea bass (Dicentrarchus labrax) aquafeeds

The aim of the current study was to evaluate the nutritional value of Lupinus albus processed with exogenous enzymes as replacer of soybean meal. Six hundred European sea bass (11.2 ± 0.0 g) were distributed in 12 tanks and fed the 4 experimental diets containing soybean meal to processed lupin meal at ratios: Control (15 %: 0 %), Lupin 1 (5 %: 7.5 %), Lupin 2 (2.5 %: 10 %), Lupin 3 (0 %: 12.5 %) in triplicate groups for 83 d. The results showed significantly higher final body weight ( P = 0.050) and specific growth rate ( P = 0.036) and lower feed conversion ratio ( P = 0.047) for the group fed the Lupin 1 diet compared to the Control diet. Significantly higher apparent digestibility coefficient of crude protein ( P = 0.043) was noted for the group tested with the Lupin 3 diet compared to Control and apparent digestibility coefficient of fat was significantly higher for groups fed the Lupin 1 ( P = 0.015) and Lupin 3 ( P = 0.000) diets compared to Control. Essential amino acid deposition was higher for the group fed the Lupin 2 diet related to the Control group and the same was observed for trypsin activity in the pyloric caeca ( P = 0.031) and intestine ( P = 0.016) of fish. Positive effect was observed in the immune status of fish fed the processed lupin meal and no histopathological alterations were determined. Comprehensively, the results proved the potential of processed lupin meal at 12.5 % to totally replace soybean meal in feed formulation for Mediterranean aquaculture marine species. • Synergen-processed lupin meal successfully replaced soybean meal in sea bass diets. • Improved key performance indices with 7.5 % inclusion of processed lupin meal. • High levels of processed lupin meal enhanced nutrient digestibility. • Processed lupin meal boosted immune response in European sea bass. • Processed lupin increased amino acid deposition and trypsin activity.