Nutritional Evaluation of Fishmeal Free Diets in European Seabass, Dicentrarchus labrax, Feeds Reared in Fresh Water

Decreases of aquaculture feed costs is one of the main targets of aqua culturists, because it represents more than 80% of the running costs. Until recently, fishmeal used in fish feeds represented a significant percentage in the composition of the diets. However, with the recent shortage and significant increases in fishmeal prices, it becomes necessary to search for alternatives that perform the same function as fishmeal and help in the process of reducing feed prices. Use of fishmeal free diets (FMFD) may be one the solutions to achieve this goal. The present study aims to evaluate FMFD for sea bass, Dicentrarchus labrax , juvenile reared in freshwater from nutritional view and study their effects on growth performance, body composition, feed utilization efficiencies and cost-benefit analysis. Five experimental FMFD were formulated to contain meat meal (MM), poultry by-product meal (PBM), mixed of MM+PBM instead of fishmeal (control) and plant protein ingredients. Methionine and lysine were supplied) when it is needed (to adjust amino acid profile in FMFDs. All the tested diets were offered to fish in triplicate tanks, two times daily, satiated for 90 days feeding period. Growth and survival rate values of fish fed FMFD containing mixture of plant protein were significantly (P<0.05) lower than those fed the control diet. However, nutritional parameters improved in case of diets had MM or PBP. Although, no significant differences (P>0.05) were observed among fish group fed diet of MM+PPM and those fed the basal diet in specific growth rate, feed conversion, protein efficiency ratio, productive protein value and energy retention. The best-feed conversion ratio was achieved with the fish group fed MM+PBP diet and it was not significantly (P>0.05) among the basal diet. Histological observations of individual villi indicated several symptoms of non-infectious sub – acute gastrointestinal enteritis in the group feeding plant protein, many of which were not present in the group feeding fishmeal. In the economic analysis, the best Profitability Index was achieved with group feeding mixed of meat meal and poultry by product meal diet, meat meal diet, poultry by product diet and fishmeal diet respectively. Therefore, the findings of this study will encourage feed manufacturers to utilize alternative proteins more efficiently in generating low-cost and sustainable aqua feeds. Fish fed diet MM+PBP gave not significant differences with the basal diet showing the possibility to unused of FM in diets sea bass juveniles reared in fresh water.