Effect of Partial and Total Replacement of Fish Meal on Growth and Body Composition of Sunshine Bass Morone chrysops×M. saxatilis Fed Practical Diets

Abstract

AbstractWith 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 chrysops×M. saxatilis) to evaluate growth and body composition when fed diets 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, with 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 daily 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), diet 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 averaged 72 g. However, final weights of sunshine bass fed diet 1 (0% FM, 30% SBM, and 31% MBM) and diet 4 (7.5% FM and 54% SBM) were significantly lower and averaged 55 g. Specific growth rate (SGR) of sunshine bass fed diet 4 was significantly lower (2.14) than fish fed diet 2 (2.70), diet 3 (2.80), diet 5 (2.68), and diet 6 (2.84), while feed conversion ratio (FCR) of fish fed diet 4 was significantly higher than sunshine bass fed diets 2, 3, 5, and 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 is replaced with a combination of animal‐ and plant‐source proteins can be fed to sunshine bass without adverse effects on weight gain, growth rate, and body composition. Further feeding trials are needed to refine diet formulations used in the present study and should be conducted in aquaria and ponds.