Effect of partial and total replacement of fish meal on growth and body composition of sunshine bass Morone chrysops x M-saxatilis fed practical diets

With the increasing emphasis to replace fish meal (FM) with less expensive protein sources in aquaculture diets without reducing weight gains, an 8-wk feeding trial was conducted with juvenile (15 g) sunshine bass (Morone chr ysops x M. saxatilis) to evaluate growth and body composition when fed diet s with different levels of FM (0, 7.5, 15, and 30%). Six practical floating diets were formulated to contain 40% protein and similar energy levels, wi th various percentages of FM, meat-and-bone meal (MBM), soybean meal (SBM), poultry by-product meal (PBM), and/or distillers grains with solubles (DGS ). Ten fish were stocked into each of 24 110-L aquaria and were fed twice d aily ad libitum (0730 and 1600 h). At the conclusion of the feeding trial, final weights of fish fed diet 2 (0% FM, 29% SBM, 29% MBM, and 10% DGS), di et 3 (0% FM, 32% SBM, and 28% PBM), diet 5 (15% FM and 44% SBM), and diet 6 (30% FM and 26% SBM) were not significantly different (P > 0.05) and avera ged 72 g. However, final weights of sunshine bass fed diet 1 (0% FM, 30% SB M, and 31% MBM) and diet 4 (7.5% FM and 54% SBM) were significantly lower a nd averaged 55 g. Specific growth rate (SGR) of sunshine bass fed diet 4 wa s significantly lower (2.14) than fish fed diet 2 (2.70), diet 3 (2.80), di et 5 (2.68), and diet 6 (2.84), while feed conversion ratio (FCR) of fish f ed diet 4 was significantly higher than sunshine bass fed diets 2, 3, 5, an d 6. Carcass (fish were decapitated) composition of sunshine bass fed diet 4 had a significantly higher percentage of moisture (70%) and protein (54% on a dry-matter basis) than fish fed all other diets. Percentage lipid was similar among fish fed all diets and averaged 41% (dry-matter basis). Results from the present study indicate that diets in which all of the FM i s replaced with a combination of animal- and plant-source proteins can be f ed to sunshine bass without adverse effects on weight gain, growth rate, an d body composition. Further feeding trials are needed to refine diet formul ations used in the present study and should be conducted in aquaria and pon ds.