Evaluation of the Nutritional Value of Seafood By-Product Blends with Red Drum Sciaenops Ocellatus and Hybrid Striped Bass Morone Saxatilis X M.Chysops

Abstract

Diets of many cultured fishes require high inclusion of fishmeal and fish oil. With the growth of aquaculture worldwide, demand for fishmeal and fish oil has increased resulting in higher prices of these ingredients due to increased demand but relatively static supplies. A promising source of alternative protein and lipid is the waste from seafood processing.

This project evaluated four different types of seafood processing wastes as potential feed ingredients for the red drum (Sciaenops ocellatus) and hybrid striped bass (Morone saxatilis x M. chysops). Viscera and skeletal remains from filleted channel catfish (Ictalurus punctatus), black drum (Pogonias cromis), yellowfin tuna (Thunnus albacares) and krill (Euphausia superba) were evaluated with red drum and hybrid striped bass by determining nutrient and energy digestibility. Catfish, black drum, and tuna waste products were blended with soybean meal in a 40:60 ratio. All diets were subjected to dry extrusion, and then dried to produce stable ingredients. Diets used for the digestibility trial were formulated to contain 40% crude protein, 10% lipid and 1% chromic oxide as a marker, with each ingredient substituted in a reference diet at a 30:70 ratio. The yellowfin tuna fillet waste also was evaluated in a comparative feeding trial with juvenile red drum. In that trial, experimental diets with the tuna by-product meal replaced menhaden fishmeal on an equal protein basis at levels of 5, 10, 20, 40 or 60%. Diets were formulated to contain 40% crude protein and 12% lipid. Juvenile red drum were fed the various diets for 7 weeks in 38-L aquaria linked as a brackish (6 + 1 ppt) water recirculating system.

Apparent digestibility coefficient (ADC) values for crude protein, crude lipid, and energy from krill and catfish meal were similar for red drum while the black drum meal had decisively lower values. Krill meal had higher ADC values for organic matter and energy than catfish meal and black drum meal in hybrid striped bass. ADC values of crude protein, and crude lipid were similar for krill, catfish, and black drum ingredients.

Based on weight gain and feed efficiency responses in the feeding trial, red drum fed the control diet with only fishmeal significantly outperformed fish fed the tuna-substituted diets. However, no significant differences were observed among fish fed the diets with 5, 10, 20, or 40% tuna substitution. These results suggest that inclusion of seafood processing by-products can be substituted for fishmeal and possibly reduce the price of fish feeds.