|dc.description.abstract||The sunshine bass Morone chrysops x Morone saxatilis has become an important fish to aquaculture in the United States favored as both a sport fish and a food fish. As with many cultured species, feed often accounts for 40-60% of total production costs. The high cost of these feeds is attributed to protein content. Sunshine bass, a carnivorous fish, requires a high protein diet (35-45%), a relatively expensive feed. Currently, fish meal (FM) is the primary source of protein in commercial sunshine bass diets, though several sources of protein, including poultry by-product meal (PBM), are available at lower costs. The use of PBM has been demonstrated to either partially or totally replace FM in diets for certain species of fish. The current study was designed to evaluate the feasibility of either partially or totally replacing FM with PBM in sunshine bass diets.
To evaluate the replacement of FM with PBM, 400 phase II sunshine bass (mean weight 5.6 g) were stocked into each of twelve 0.04-hectare earthen ponds. The ponds were randomly assigned one of four diets formulated to be isonitrogenous (37% protein) and isocaloric with various percentages of PBM (0, 16.5, 33.0, and 49.3% of total protein; diet 1-4 respectively) partially or totally replacing FM (0, 33, 67, and 100% of FM protein content). The necessary feed formulations were commercially extruded into a floating pellet. Fish were fed twice daily, in the morning and evening, below satiation. Feeding rates were based on a percentage of estimated body weight. Fish were cultured for 246 days. No significant differences (p < 0.05) in total harvest weights (173 kg) and net production (4257 kg ha-1) were found among any of the treatment diets. No significant differences were found in mean individual fish weights (511 g), perecent filet weights (49%), percent survival (85%), percent weight gain (9100%), feed conversion ratio (2.47), specific growth rate (1.84), protein conversion efficiency (65%), and percent intraperitoneal fat (9.8%). The hepatosomatic index (HSI) was significantly different between two treatments. The HSI for Diet 3 (3.7%) was significantly higer than Diet 4 (3.2%). Proximate analysis (percentage of moisture, protein, lipid, and ash) of whole fish and fish fillets also revealed no significant differences among all treatments.
Proximate analysis was performed on the four treatment diets. A significant difference (p < 0.05) was found in the protein content between diet 3 (34.43 % protein; 67% FM replacement) and the remaining three treatment diets (37% protein). Amino acid analysis of the four diets also revealed a possible deficiency of methionine in diets 3 and 4.
Results indicate that complete replacement of FM with PBM is feasible in grow-out diets for sunshine bass grown in earthen ponds. The total replacement of FM with PBM yielded no significant differences (p < 0.05) in production, dress-out, or body composition. Economic analysis indicates that replacement of FM with PBM may result in reduced revenue over feed costs.||en_US