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 s olubles, the coproducts from ethanol fermentation of corn, were incorp orated in tilapia diets with 32 and 28% protein. The diets were balanc ed in amino acid composition by addition of soy flour and/or synthetic lysine and tryptophan. The diets were fed to tilapia fry of average i nitial weight of 0.5 g in aquaria for 8 weeks. Weight gain expressed a s percentage increase after 56 days were best (P < 0.05) for a 28% pro tein diet with 67% corn gluten feed and 26% soy flour, a 32% protein d iet with 54% corn gluten feed and 39% soy flour, and the control diet with 32% protein. Weight gain was positively correlated with protein c ontent, 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 a nd tryptophan and 28% protein diet with 67% corn gluten feed and 26% s oy flour also resulted in the same feed conversion ratio and protein e fficiency ratio (P > 0.05) as the control diet. Fish fed the remaining two 28% protein diets exhibited higher feed conversion ratio and lowe r 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 conversio n ratio, and protein efficiency ratio.