56 SEPTEMBER 2012 be used without adversely affecting performance. Growth, feed conversion, protein retention, survival, carcass composition, and organoleptic properties of fillets were not affected by diet at this inclusion level of DDGS. One study (Robinson and Lee 2008) suggested that supplementation with lysine at 30 percent DDGS is necessary to support satisfactory growth. Body fat increases for fish fed a DDGS diet compared to fish fed a control diet (Robinson and Li 2008; Lim et al. 2009). Overall, DDGS is considered an acceptable ingredient in diets for channel catfish (Tidwell et al. 1990, Webster et al. 1991). • Rainbow Trout Oncorhynchus mykiss Apparent digestibility coefficients of nutrients in DDGS for rainbow trout are high (Cheng and Hardy 2004a). However, one of the limitations of using DDGS in rainbow trout diets is the relatively low concentrations of lysine and methionine, which are much lower than in fishmeal. Therefore, supplementation with synthetic lysine and methionine is necessary to achieve satisfactory growth performance. DDGS, without synthetic lysine and methionine supplementation, can be added to the diet up to 15 percent, or replace up to 50 percent of the fishmeal to achieve satisfactory growth performance (Cheng and Hardy 2004a). At 50 percent replacement of fishmeal with DDGS, performance can improve with methionine supplementation (Cheng et al. 2003). DDGS can be included at 22.5 percent, or replace up to 75 percent of fishmeal in rainbow trout diets, with both lysine and methionine supplementation. Phytase supplementation (up to 1200 FT/kg diet) improves apparent digestibility of nutrients (dry matter, fat protein, energy, amino acids, minerals) in diets containing 30 percent DDGS (Cheng and Hardy 2004b). For diets with 15 percent DDGS and supplemented with lysine, methionine and phytase, the increased availability of minerals suggests that trace mineral supplementation could be reduced when phytase is added to diets. For diets containing maize gluten meal and maize DDGS, the extent of fishmeal replacement in the diet depends on the ratio of DDGS to gluten meal (Stone et al. 2005). Up to 18 percent dietary inclusion of these maize co-products can replace about 25 percent of the fishmeal in practical diets without adversely affecting growth performance. Extrusion of diets containing maize DDGS and gluten meal is of no benefit compared to feeding cold-pelleted diets. • Nile Tilapia Oreochromis niloticus Feeding diets containing 32 to 40 percent protein and 16 to 49 percent DDGS result in good growth and production performance of fry (Wu et al. 1996). The best performance is achieved by feeding a 36 protein commercial diet or a 40 percent protein diet containing 35 percent DDGS. For fingerlings, DDGS can be included up to 29 percent in diets with 32 to 36 percent crude protein (Wu et al. 1994). Diets (28 percent protein) containing 82 percent DDGS and supplemented with synthetic lysine and tryptophan provide similar performance to a 32 percent protein diet (Wu et al. 1997). DDGS and other maize co-products, with synthetic amino acid supplementation, can be used to formulate all plantbased diets and replace all of the fishmeal when feeding juvenile tilapia. Growth of tilapia fed a pelleted DDGS diet is greater than that of fish fed an unpelleted DDGS diet (Tidwell et al. 2000). Although growth increases significantly for fish fed a commercial catfish diet, the cost of production is significantly greater ($0.66/kg gain) compared to fish fed unpelleted ($0.26/ kg gain) and pelleted ($0.37/kg gain) DDGS diets. Up to 20 percent DDGS can be added to the diet as a partial substitute for soybean meal and corn meal without affecting growth performance, body composition, hematology, immune response and resistance to a Streptococcus iniae infection in juvenile tilapia (Lim et al. 2007). In a study where soybean meal was replaced by DDGS, the best growth rate and feed conversion of fingerling was measured in fish fed diets containing 0 percent, 25 percent, or 50 percent DDGS supplemented with phytase (Abo-State et al. 2009). There is no difference in apparent digestibility of diets containing as much as 27.5 percent DDGS, although feed conversion was best in fingerlings fed a diet with 17.5 DDGS (Schaeffer et al. 2009). The performance of Nile tilapia fed 20 to 30 percent DDGS diets is similar. DDGS can be a highly economical feed ingredient in tilapia diets and can be used successfully at relatively high dietary inclusion rates (20 to 30 percent), if deficient amino acids are provided as supplements. • Sunshine Bass Morone chrysops x M. saxatilis The apparent digestibility of protein in sunshine bass fed practical diets containing DDGS (65 percent) was less than diets containing fishmeal (86 percent) (Thompson et al. 2008). The apparent digestibility of organic matter in fish fed DDGS diet (17 percent) was much lower than diets containing fishmeal (89 percent). The quality of the DDGS source used in this study was not defined, but was likely of inferior quality because the protein and organic matter digestibility was poor. These results contrast with results of other studies with other species where DDGS inclusion in diets provided satisfactory growth performance. • Freshwater Prawn Macrobrachium rosenbergii Levels of up to 40 percent DDGS can be included in practical diets for prawns stocked at a density of 19,760/ha to achieve good performance (Tidwell et al. 1993a, 1993b). Replacement of fishmeal with soybean meal and DDGS increases dietary levels of glutamine, proline, alanine, leucine and phenylalanine and decreases aspartic acid, glycine, arginine and lysine levels in diets (Tidwell et al. 1993b). Fatty acid profiles of diets also change when soybean meal and DDGS replace fishmeal. Concentrations of 16:0, 18:2n-6, and 20:1n-9 increase and concentrations of 14:0, 16:1n-7, 18:1n9, 18:3n-3, 20:5n-3, 22:5n-3 and 22:6n-3 decrease. Fishmeal can be partially or totally replaced with soybean meal and DDGS in diets for freshwater prawns raised in ponds in a temperate climate. Furthermore, DDGS can be consumed directly by juvenile prawn (> 2 g); thus, DDGS may serve a dual role as feed and pond fertilizer (Coyle et al. 1996).
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