|dc.description.abstract||Feed is generally the largest expenditure in semi-intensive and intensive catfish culture operations, and protein is the most expensive component of feeds. Efforts to reduce feed costs have resulted in increased use of plant proteins in diet formulations as replacements of expensive animal ingredients. Currently, soybean meal (SBM) comprises 30 to 40% in commercial grow-out feeds for catfish. Replacement of SBM with less expensive protein sources would be beneficial in reducing feed costs. Distiller’s dried grains with solubles (DDGS), a co-product of the ethanol distillery industry, is less expensive than SBM on a per unit protein basis. In 2001, the U.S. produced about 3.1 million tons of DDGS. As a result of the recent expansion and increase in ethanol production for fuels due to the shortage and rising cost of petroleum-based fuel, and to reduce pollution , the production of DDGS in the U.S. has been reported to increase to approximately 8 million tons in 2006 (Shurson 2006).
To evaluate the effects of the dietary levels of DDGS with and without lysine supplementation on growth, feed intake, feed efficiency of a catfish growth trial, two different catfish spices were chosen, channel catfish (Ictalurus punctatus) and hybrid catfish (channel catfish × blue catfish Ictalurus furcatus). Channel catfish were reared in earth pond and hybrid catfish in an indoor intensive water reuse system using the same formulation of five different feeds. Five diets (diets 1-5) were formulated to contain approximately 32% crude protein and 2,900 kcal of digestible energy/kg (NRC 1993). The diets were consisted of a basal (control) diet and diets containing 20 and 30% DDGS, with and without the addition of lysine to the level equal to that of the basal diet. The test diets were formulated as partial replacements of a mixture of soybean meal (SBM) and corn meal (CM) on an equal protein basis. Lipid levels in all diets were maintained constant by the addition of fish oil. Diets were processed into floating pellets by a local Feed Mill.
Based on statistical analysis of the result, there are no significant difference among all treatments for the measured parameters in both species including survival rate, weight gain, feed intake, FCR, final size etc. Under the reported conditions, lysine supplementation may be omitted from theses diet formulations for channel catfish reared in earthen pond conditions and hybrid catfish reared in intensive system. Consequently, the feed cost in channel catfish production as well as hybrid catfish production can be further reduced by omitting the lysine supplementation for these formulations. Based on these results further research should focus on challenges using higher levels of DDGS as well as the possibility of immune stimulation by DDGS.||en