EFFECTS OF REPLACING FISH MEAL BY A BLEND OF FERMENTED CANOLA MEAL AND SOY PROTEIN CONCENTRATE IN DIETS FOR JUVENILES RED SEA BREAM Pagrus major

Serge Dossou*, Shunsuke Koshio, Manabu Ishikawa, Saichiro Yokoyama, Philippe Lalèyè, Antoine Chikou, Mahmoud A.O. Dawood, Mohammed F. El Basuini, Olivier Adissin and Amr I. Zaineldin

Laboratory of Aquatic Animal Nutrition
Faculty of Fisheries, Kagoshima University, Shimoarata 4-50-20, Kagoshima, Japan
sergedos@yahoo.fr

With the growing demand and high cost of protein sources in aquaculture, Rapeseed/Canola (CM) has become one of the most viable sources of plant protein because of the volume of production and its protein's nutritional and functional qualities. However, antinutritional factors in CM may restrict fish growth and affect protein utilization and health status of fish. Solid state fermentation has been shown to improve nutritional qualities of feedstuffs and leads of lowering food allergy, enhancing antioxidant activities and immune stimulator compounds in meals. Therefore, the present study was conducted to investigate the effects of using Aspergillus oryzae fermented CM (FCM) and Soy protein concentrate (SPC) as major dietary protein sources on red sea bream performances.

Five isonitrogenous and isocaloric diets were formulated replacing FM by a blend (2:1) of FCM and SPC to achieve an FM protein substitution level of 0% (FP0), 25% (FP25), 50% (FP50), 75% (FP75) and 100% (FP100) respectively. Triplicate groups of twenty fish were assigned to each dietary treatment for a 56-days feeding trial. FP25 fed group showed significantly higher (P < 0.05) growth performances than all other groups. However, there were non-significant differences (P > 0.05) in survival, feed/protein efficiency ratio in groups fed FP0, FP25 and FP50 diets. Blood total Cholesterol level followed the same trend. Triglyceride, blood urea nitrogen, glutamyl oxaloacetic transaminase, lysozyme and peroxide activities remained unchanged with the inclusion of the blend. Feed intake was unchanged in all dietary treatments but 75% and 100% substitution levels significantly reduced (P < 0.05) growth and feed/protein efficiency ratio. These effects could be related to reduced digestibility due to an increased dietary phytic acid.

These findings suggest that FM may be reduced to 24% (50% replacement) with FCM and SPC blend without detrimental effects on overall performances of red sea bream. Moreover, we recommend 25% replacement as this level has recorded the best growth, immune responses and anti-oxidative stress activities.