THE USE OF SOYBEAN-MEAL AS A REPLACEMENT FOR FISH-MEAL IN DIETS FOR HYBRID STRIPED BASS (MORONE-SAXATILIS X MORONE-CHRYSOPS)

A series of feeding trials was conducted to determine the feasibility of using soybean meal to partially replace fish meal in diet formulations for hybrid striped bass. Pelleted diets were formulated with soybean meal (supplemented with methionine) replacing either 25, 50, or 75% of the protein from fish meal. Diets were fed at 4% of body weight, adjusted periodically for change in weight. Growth parameters and feed efficiencies were compared to a fish-meal-based control diet. All diets were isocaloric (14.6 kJ GE (gross energy)/g) and isonitrogenous (35% crude protein). In 12-week laboratory trials, fish (5 g initially) gained 4 times their original weight. Feed efficiencies were not significantly different and ranged from 1.2 to 1.8 g fed/g gain after 12 weeks. At the end of 6 weeks, only those fish fed 25% soybean meal protein diet grew as well as those fed 100% fish-meal-based diet. However, by the end of 12 weeks, there was no significant difference in weight gain of fish fed diets with either 25 or 75% of protein from soybean meal as compared to the fish meal control diet. In 8-week feeding trials at 19 degrees C, using larger fish (100-150 g), there was no significant difference among weight gain of fish fed 0, 25, 50, or 75% of dietary protein as soybean meal. Mean weight gains ranged from 122 to 140 g. In the 14-week pond trial, with fish weighing 100-200 g, there was no significant difference in weight gains of fish fed 100% of their dietary protein as fish meal and those fed a diet with 50% of the protein replaced with soybean meal. Weight gains averaged 338-352 g. These data indicate that, at least for larger hybrid striped bass, up to 75% of the fish meal protein in diets can be replaced with soybean meal protein.