Growth Response and Feed Utilization of Juvenile Hybrid Catfish Fed Diets Containing Distiller's Dried Grains with Solubles to Replace a Combination of Soybean Meal and Corn Meal

—A feeding trial was conducted in aquaria with juvenile hybrid catfish (channel catfish Ictalurus punctatus3blue catfish I. furcatus) to evaluate distiller’s dried grains with solubles (DDGS) as a replacement for a combination of soybean meal (SBM) and corn meal (CM). Twenty-five 75-L glass aquaria were each stocked with 30 juvenile hybrid catfish (initial weight1⁄4 1.16–1.25 g). Five replicates were randomly assigned to each of five dietary treatments. Diet 1, the basal diet, contained 32% SBM and 20% CM (no DDGS and no lysine supplementation) and was based on a practical diet formulated for channel catfish. Diet 2 contained 20% DDGS and 0% lysine supplementation; diet 3 contained 20% DDGS and 0.10% lysine supplementation; diet 4 contained 30% DDGS and 0% lysine supplementation; and diet 5 contained 30% DDGS and 0.20% lysine supplementation. Fish were fed at a restricted rate equaling 5% of wet body weight twice daily for 8 weeks. There were no significant differences in percent weight gain or final weight among the four treatments with DDGS supplements. However, weight gain and final weights of fish offered diet 1 were significantly poorer than those of fish offered diets 3–5. These diets also produced significantly lower feed conversion ratios and higher protein efficiency ratios than diet 1. Results of the present study indicate that the diets formulated with 30% DDGS using the reported combination of other protein sources were not deficient in lysine and supported good growth and feed utilization in juvenile hybrid catfish. Feed is generally the largest expenditure in semiintensive and intensive fish culture operations, and protein is the most expensive component of feeds. Efforts to reduce feed costs have resulted in increased use of plant proteins as replacements for expensive animal ingredients, especially fish meal, in diet formulations. Because of its high protein content, high digestibility, relatively well-balanced amino acid profile, reasonable price, and steady supply, soybean meal (SBM) is widely used as a cost-effective feed ingredient for many aquaculture animals (Storebakken et al. 2000). However, other plant protein sources generally cost less than both fish meal and SBM; thus, replacing SBM with less-expensive plant protein sources would be beneficial in reducing feed costs. Distiller’s dried grains with solubles (DDGS) constitute a coproduct of the ethanol distillery industry. As a result of the recent expansion and increase in ethanol production for fuels and to reduce pollution, the production of DDGS in the USA increased to more than 7 million metric tons in 2006 (Shurson 2006). This product has a relatively high protein content (;30% crude protein) without the presence of antinutritional factors commonly found in most plant protein sources. Results of earlier studies have shown that based on growth performance and feed utilization efficiency, the DDGS product is a promising feed ingredient for several fish species, including rainbow trout Oncorhynchus mykiss (Cheng and Hardy 2004), * Corresponding author: [email protected] Received January 11, 2010; accepted March 30, 2010 Published online June 30, 2010 298 North American Journal of Aquaculture 72:298–303, 2010 Copyright by the American Fisheries Society 2010 DOI: 10.1577/A10-002.1 [Article] D ow nl oa de d by [ U ni ve rs ity o f M in ne so ta L ib ra ri es , T w in C iti es ] at 0 8: 53 0 1 Se pt em be r 20 11 tilapias Oreochromis spp. (Wu et al. 1996), and channel catfish Ictalurus punctatus (Lovell 1980; Tidwell et al. 1990; Webster et al. 1991, 1992, 1993). At least four species of ictalurid catfishes have been considered as candidates for commercial aquaculture in the USA. Channel catfish and blue catfish I. furcatus are the best two species for aquaculture (Tucker and Robinson 1990; Dunham et al. 1993). Compared with blue catfish, the channel catfish has faster growth-tomarket size, better tolerance for low dissolved oxygen, and superior resistance to some diseases (e.g., columnaris). However, the blue catfish also has superior resistance to certain diseases (e.g., enteric septicemia of catfish), has better carcass traits, and is easier to harvest by seine (Dunham and Argue 2000). Research on hybrids of female channel catfish 3 male blue catfish has demonstrated that they exhibit many commercially desirable characteristics. Compared with most commercially cultured strains of channel catfish, this hybrid exhibits superior characteristics for the following traits: faster growth, tolerance of low dissolved oxygen, increased resistance to many diseases, tolerance to crowded growth conditions in ponds, uniformity in size and shape, higher dress-out percentages, and increased harvestability by seining (Wolters et al. 1996; Masser and Dunham 1998). Published data on the nutrition of channel catfish 3 blue catfish hybrids are limited. The objective of this study was to investigate the growth response and feed utilization of juvenile channel catfish 3 blue catfish hybrids (hereafter, hybrid catfish) fed diets containing 20% and 30% DDGS with and without lysine supplementation as replacements for a combination of SBM and corn meal (CM) in the basal diet.