Use of Corn-Derived Ethanol Coproducts and Synthetic Lysine and Tryptophan for Growth of Tilapia (Oreochromis niloticus) Fry

Corn gluten meal, corn gluten feed, and corn distillers' grains with solubles, the coproducts from ethanol fermentation of corn, were incorporated in tilapia diets with 32 and 28% protein. The diets were balanced in amino acid composition by addition of soy flour and/or synthetic lysine and tryptophan. The diets were fed to tilapia fry of average initial weight of 0.5 g in aquaria for 8 weeks. Weight gain expressed as percentage increase after 56 days were best ( P < 0.05) for a 28% protein diet with 67% corn gluten feed and 26% soy flour, a 32% protein diet with 54% corn gluten feed and 39% soy flour, and the control diet with 32% protein. Weight gain was positively correlated with protein content, lysine/protein, and protein/energy. Fish fed 32% protein diets exhibited the same feed conversion ratio and protein efficiency ratio ( P > 0.05) as the control 32% protein diet. Fish fed 28% protein diet with 82% corn distillers' grains with solubles and synthetic lysine and tryptophan and 28% protein diet with 67% corn gluten feed and 26% soy flour also resulted in the same feed conversion ratio and protein efficiency ratio ( P > 0.05) as the control diet. Fish fed the remaining two 28% protein diets exhibited higher feed conversion ratio and lower protein efficiency ratio ( P < 0.05) than fish fed the control diet. It appears the 28% protein diet with 67% corn gluten feed and 26% soy flour is adequate for tilapia fry based on weight gain, feed conversion ratio, and protein efficiency ratio. Keywords: Tilapia; corn gluten meal; corn gluten feed; corn distillers' grains with solubles; synthetic amino acids; weight gain; feed conversion ratio; protein efficiency ratio