Evaluation of distillers' grains with solubles as a protein source in diets for channel catfish

Abstract

A 12-week feeding trial was conducted in aquaria with juvenile (10 g) channel catfish ( Ictalurus punctatus) to evaluate the use of distillers' grains with solubles (DGS) as a partial replacement for soybean meal in a prepared diet. In three diets, DGS were added at 0, 35, and 70% of the diet. A fourth diet also contained 70% DGS, but was supplemented with 0.4% crystalline L-lysine (70% DGS+LYS). All diets were isonitrogenous (36% crude protein) and isocaloric (2.7 kcal/g of diet). Fish fed the 35% DGS and 70% DGS+LYS diets were significantly larger (total length), had greater weight gains, and higher specific growth rate (SGR) than fish fed a diet with 70% DGS without supplemental lysine ( P<0.05). No significant differences ( P > 0.05) were found in weight gain, food conversion ratio (FCR), and SGR in fish fed the 35% DGS, 70% DGS+LYS, or the control (0% DGS) diets. These data suggest that growth in channel catfish juveniles fed a diet with 35% DGS is equivalent to that in fish fed a commercially formulated diet with a high proportion of soybean meal. A diet containing 70% DGS appeared to be lysine-deficient for juvenile channel catfish since the addition of crystalline lysine to the diet significantly improved growth rate.