Evaluation of growth performance, condition indices and body composition of juvenile red drum (Sciaenops ocellatus) fed fishmeal- and fish-oil-free diets

Abstract

In the current study, six isonitrogenous (50% CP) experimental diets composed of practical ingredients were formulated to evaluate the complete replacement of either menhaden fishmeal (FM), menhaden fish oil (FO) or both FM and FO with juvenile red drum. The experimental control diet (FM + FO) contained FM at 28.3% of dry weight and FO at 6.5% of dry weight and met all established nutrient requirements of red drum. A fishmeal-free diet (FMF + FO) had FM completely replaced with a combination of hydrolyzed soy product, poultry by-product meal and soy protein concentrate but contained menhaden fish oil at 7.7% of dry weight. All other experimental diets were isolipidic (13% crude lipid) and contained no FM or FO and had FO replaced by various combinations of canola, flax, and algal oils. Groups of 15 fish (~4.4 g/fish initial weight) were stocked in 28, 38-L aquaria fashioned as a recirculating aquaculture system operated at 7 ppt salinity. Quadruplicate aquaria of fish were randomly assigned to each diet and fed to apparent satiation twice daily for an 8-week duration. Red drum fed the five experimental diets which replaced FM and/or FO did not show any significant differences in percentage weight gain, feed efficiency (FE), protein conversion efficiency (PCE), fillet yield, or survival compared to fish fed the control diet which included both FM and FO. Whole-body proximate analysis of red drum fed the experimental diets revealed no significant differences in crude protein content. The current study provides evidence that juvenile red drum can be successfully raised using practical diets devoid of FM and FO with performance similar to fish fed a control diet with considerable amounts of both FM and FO.