Evaluating the Use of Modified Corn Distillers Grains as a Fish-meal Protein Replacement in Yellow Perch Perca flavescens

Aquaculture relies heavily on marine-derived fish meal (FM) as a primary feed ingredient. Industry growth, high demand and increasing cost of finite FM supplies create urgency to find alternative protein sources. Plant products having sufficient nutrient composition and no anti-nutritional factors offer a viable alternative to conventional FM based diets. A grain ethanol product stream called distillers grains (DG) offers a potential alternative. DG can be split into two broad classes. Distiller’s wet grains (DWG) are the solids portion of corn material remaining after distillation and centrifugation. Distiller’s dried grains with solubles (DDGS) are produced by mixing the DWG the condensed centrifuge supernatant (aka. Corn syrup), and then drying. A new generation of DG called high-protein distiller grains (HP-DG) adds additional processing to base DG to produce a higher value material with an enhanced nutrient profile. Two Yellow Perch (Perca flavescens) feeding trials evaluated the performance of HP-DG against a fish meal (positive) control and an unconverted DG (negative) control. The first feeding trial evaluated HP-DG’s produced through different processing methods including: fermentation, chemical extraction (CE), and mechanical fractionation (MF). A second trial evaluated HP-DG’s produced through solid state and submerged fermentation processes on both DWG and DDGS substrates. Apparent digestibility of HP-DG’s top performers was also evaluated. Trial one was performed for 16 weeks. Growth metrics and health indices were compiled following completion. The fish meal control showed the greatest relative growth (44437.63 g), while two HP-DG diets; Solid State fermented (SS) DWG (33352.05 g; P=0.21) and SS DDGS (31440.44 g; P=0.37) demonstrated statistically similar performance. Specific growth rate (SGR) followed a similar performance trend, with fish meal (2.01) outperforming all corn-based diets. Submerged fermented DWG showed significantly diminished performance (