Submitted to: Journal of Applied Aquaculture
Publication Type: Peer reviewed journal
Publication Acceptance Date: 6/1/2005
Publication Date: 8/1/2005
Citation: Stone, D.A., Hardy, R.W., Barrows, F. 2005. Effects of extrusion on nutritional value of diets containing corn gluten meal and corn distiller’s dried grain for rainbow trout, onchorhynchus myskiss.. Journal of Applied Aquaculture. 17(3):1-20. Interpretive Summary: Fish meal from capture fisheries in the ocean has been the main protein source in diets for farm-reared fish for many years due to its low cost and availability. The increasing demand for fish meal by animal production industries, increasing waste water regulation, and high levels of organic contaminants found in fish meal, are causing an increased interest in alternatives to fish meal. We evaluated the effect of processing technology on the nutritional quality of corn gluten meal and corn distillers dried grains (CDDGS). The combination of these two ingredients did not prove to be an effective replacement for fish meal. Extrusion cooking increased growth of fish fed the control feed, but adding the corn mixture reduced or eliminated this beneficial effect. The indigestible fiber in the CDDGS is of no benefit to trout and probably caused the observed decrease in performance.
Technical Abstract: The effects of processing methods on diets containing increasing levels of a combination of corn distiller’s dried grain with solubles (CDDGS) and corn gluten meal (CGM) to replace fish meal in diets of rainbow trout were investigated. A two by four factorial treatment arrangement was used with two types of diet processing methods (cold-pelleted and extruded) and four levels of corn products replacing fish meal protein (0,25,50,75%). There was an effect of processing method and level of corn products on weight gain and feed conversion ratio, and an interaction of those effects. Extrusion of diets containing the corn products did not improve fish growth compared to fish fed the cold-pelleted feed (extrusion of the wheat containing diet did improve weight gain and feed conversion). There were interactions between process type and level of corn products on protein retention efficiency, and apparent digestibility coefficients for both dry matter and energy. The presence of indigestible carbohydrate in the CDDGS limited replacement of fishmeal with the corn products to 18% of the protein.