Sea Clam-Derived Feeding Stimulants Enhance Acceptability and Intake of Reduced Fish Meal, Soy-Based Sunshine Bass Feeds

Fish meal sparing or replacement is limited by reduced diet acceptability and feed intake, particularly among carnivorous finfish. Two 8-week feeding trials were conducted to assess whether the inclusion of sea clam (ocean quahog Arctica islandica) processing by-products could improve the intake of reduced fish meal feeds in sunshine bass (female White Bass Morone chrysops x male Striped Bass M. saxatilis). In trial 1, juvenile fish (31.9 +/- 0.2 g, average initial weight) were cultured at 18.5 +/- 2.4 degrees C and fed diets containing 30% fish meal (hereafter, "FISH"), 6.7% fish meal (remainder of dietary protein primarily provided by soybean meal; hereafter, "SOY"), or the reduced fish meal formulation amended with 1% dried clam juice (hereafter, "SOY + clam juice"), dried clam fines (hereafter, "SOY + clam fines"), or betaine as feeding stimulants. In trial 2, fish were slightly smaller at the outset (18.4 +/- 0.3 g) and cultured at 27.3 +/- 0.2 degrees C. Growth performance was generally superior among fish reared in trial 2, but both trials yielded similar results in terms of dietary treatments. Feed intake and growth were reduced among fish fed the SOY feed compared with those fed the FISH feed. The addition of betaine to the reduced fish meal formulation did not improve diet acceptance or intake. However, the inclusion of clam by-products improved feed intake and growth, with both the SOY + clam juice and SOY + clam fines feeds yielding growth equivalent to the FISH feed. Semiquantitative evaluations of feeding behavior suggest that dietary treatment effects were rooted in differences in feed acceptability and that the inclusion of clam by-products had a corrective effect on the comparatively indifferent feeding observed among fish fed the SOY diet. The inclusion of sea clam by-products, particularly dried clam fines, improved the intake of the reduced fish meal formulation, and these by-products appear to be effective feeding stimulants in soy-based feeds for juvenile sunshine bass grown in tanks.