Replacement of fish meal by animal by-product meals in a practical diet for grow-out culture of grouper Epinephelus coioides

Abstract

A feeding trial was conducted to evaluate the potential of replacing fish meal with processed animal by-product meals, meat meal and blood meal (4:1 ratio), in practical diets for juvenile grouper (Epinephelus coioides). Eight isonitrogenous diets were formulated to contain 45% protein and 12% lipid. Fish meal was replaced by 0%, 10%, 20%, 30%, 40%, 60%, 80%, and 100% of meat meal and blood meal (4:1) mixture (diets 1–8). The diet with 100% fish meal (diet 1) or trash fish as feed (diet 9) were used as controls. Grouper juveniles were reared in 250-l circular fiberglass tanks maintained in a flow-through seawater system. Each dietary treatment was tested in quadruplicate groups of 25 fish per tank arranged in a completely randomized design. Fish were fed the diets twice per day at a daily feeding rate of 5–6% of biomass and trash fish at 10–12% of biomass for 60 days. Percentage weight gain, specific growth rate (SGR), survival, feed conversion ratio (FCR) and body composition of grouper juveniles were measured. There were no significant differences (P>0.05) in growth performance among fish fed diets 1–7 (0–80% fish meal replacement) with those fed diet 9 (trash fish as feed). However, fish fed diet 3 had significantly higher (P<0.05) growth than those fed diet 8 (100% fish meal replacement). Survival among fish fed the experimental diets did not significantly differ (96–100%) but was significantly higher (P<0.05) than survival (90%) of fish fed trash fish. These results showed that up to 80% of fish meal protein can be replaced by processed meat meal and blood meal coming from terrestrial animals with no adverse effects on growth, survival, and feed conversion ratio of E. coioides juveniles.