Nutritional Value of Diets Containing Distiller's Dried Grain with Solubles for Rainbow Trout, Oncorhynchus mykiss

Abstract

A feeding trial using corn distiller's dried grain with solubles (DDGS) was conducted to evaluate the nutritional value of DDGS and effects of lysine and methionine supplementation in DDGS-based diets on the performance of rainbow trout, Oncorhynchus mykiss. The DDGS-based diets were made such that DDGS was used at 7.5% (diet 2), 15% (diet 3), and 22.5% (diet 4) inclusion levels without supplementing crystalline L-lysine-HCl and DL-methionine, and was used at 7.5% (diet 5), 15% (diet 6), and 22.5% (diet 7) with lysine and methionine supplementation in a 2 × 3 factorial design. A fish meal-based diet (diet 1) was used as a control. The control and lysine and methionine supplemented diets contained 2.2% lysine and 1.1% methionine. A total of 630 fish (initial body weight 49.8 g) were randomly stocked into twenty-one, 150-L tanks with 30 fish/tank and 3 tanks/diet. Fish were fed to apparent satiation 3 times/day and 6 days/week. After a 6-week growth period, weight gain (WG) offish fed diets 1 to 7 was: 48.9, 43.9, 46.5, 42.9, 51.3, 54.3, and 46.4 g, respectively. Feed conversion ratio (FCR) offish fed diets 1 to 7 was: 1.21, 1.35, 1.25, 1.34, 1.20, 1.11, and 1.29 g diet/g gain, respectively. Survival was 100% for fish fed all diets. Two-way ANOVA showed that lysine and methionine supplementation improved WG (P = 0.0002) and FCR (P = 0.0011). Fish fed diets containing 15% DDGS, or replacing 50% offish meal on isonitrogenous and isocaloric basis, were not significantly different from fish fed the fish meal-based diet in terms of WG, FCR, and survival (P > 0.05), indicating that DDGS could be used at the 15% inclusion level, or replace up to 50% offish meal. Furthermore, DDGS could be used at the 22.5% inclusion level, or replace up to 75% of fish meal in rainbow trout diets with lysine and methionine supplementation.