Evaluation of Six Selected Commercial Fermented Soybean Meal by Feeding Juvenile Turbot (Scophthalmus maximus L.)

Various kinds of fermented soybean meal are now commercially available, whereas the quality of these products is uneven due to different processing technologies, fermentation strains, and raw soybean meal, which would lead to different effects on bioavailability of nutrients in aquaculture feeds. Thus, a 10-week feeding trial was conducted to evaluate the effects of six different commercially available fermented soybean meal (FSBM) on growth performance of juvenile turbot (Scophthalmus maximus L.) and to analyze the correlation between growth parameters and FSBM components. Seven isonitrogenous and isolipidic diets were formulated: fish-meal-based diet (the control group, FM) and FM with 450 g/kg of fish meal substituted by six commercially available FSBM (the replacement groups, FSBM1, FSBM2, FSBM3, FSBM4, FSBM5, and FSBM6). Results showed that specific growth rate (SGR) and weight gain rate (WGR) were significantly higher in groups FMSB3 and FMSB4 than in other replacement groups, but significantly lower in the control group. Besides, no significant differences were observed in feed efficiency ratio (FER) and protein efficiency ratio (PER) among groups FSBM3, FSBM4, and FM. Correlation analysis revealed that SGR, PER, and protein retention (PR) of turbot were all positively correlated with the water-soluble protein and trichloroacetic acid- (TCA-) soluble protein content of FSBM, but negatively correlated with the content of trypsin inhibitor. In summary, the commercial FSBM3 and FSBM4 could yield higher growth performance of juvenile turbot than the rest selected FSBM when replacing 450 g/kg of fish meal in diets, and the content of water-soluble protein, TCA-soluble protein, and trypsin inhibitor could serve as relatively accurate indicators in the quality evaluation of FSBM.