Evaluation of traditional diet and corn gluten feed substituted alternative diet for pond-raised hybrid catfish on production and xanthophyll level

In the United States, catfish industry is a mature industry with a long history of success. However, the industry faces numerous challenges while it evolves and adapts to shifting inputs and market demands, such as the dramatic increase in the price of feed ingredients and requests for more consistent fillet color. There is considerable interest in reducing the cost of production diets either by reducing the protein content or by using alternative ingredients such as corn gluten feed. Towards this goal, a pond study was conducted to evaluate the utilization of alternative feed containing 20% corn gluten feed compared to traditional feed without corn gluten feed for the production of channel-blue hybrid catfish. Both alternative and traditional feeds were formulated with two protein contents (28% and 32%). In addition to traditional parameters, the xanthophyll contents on the fish fillets were determined. Upon initiation of the pond trial, 600 hybrid catfish fingerlings were stocked in each of 20 0.04-ha ponds, with a mean weight of 34.5 g/fish. Fish were fed four experimental diets once daily to apparent satiation over a summer growing season. No significant differences were found in growth performance and feed utilization among the four treatments, including gross and net yield, total amount of feed fed, estimated feed conversion ratio and survival. No significant differences were found in mean individual fish weight and mean total body length at harvest, relative weight index and dressout (headed and gutted). However, intraperitoneal fat ratio was significantly lower in fish fed the alternative feeds indicating lower energy content of the diet. No significant differences were observed in hematology and immune response indices. Xanthophyll levels in diets and in fillet were linearly related, but without discernible yellow color. These data generally indicate that channel-blue hybrids can efficiently utilize all the four experimental diets with satisfying production result. (C) 2012 Elsevier B.V. All rights reserved.