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Materials and Methods

Diets The compositions of the experimental diets are listed in Table 1. The extrusion conditions and proximate composition of corn meal were as described previously. ll> Because the diets for each experiment were prepared separately, there were some variations in the nutrient content. Diet 2 was used for prefeeding. Raw and extruded corn meal were mixed in three different proportions in the diets (40: 0, 20: 20, and 0: 40). The resulting level of starch in the diets was around 32%. Except for cellulose and carboxymethyl cellulose (CMC), the rest of the ingredients were included at the same level in all diets and were formulated to satisfy the nutritional requirements of common carp. 12) Casein was used as a protein source. In diet 1, 5% cellulose was replaced by CMC as a binder because raw corn meal has no binding properties. Chromic oxide was included in the diets in order to measure the apparent digestibility. The experimental diets were fed in a dry pellet form.