Growth performance of Oreochromis niloticus fed diets in which cooked soybean replaced fish meal

Abstract

Five experimental diets were formulated. In the control diet fishmeal was used as the sole source of dietary protein. The protein of the fishmeal in the control diet was replaced with varying levels of dehulled and cooked soybean meals at 0%, 25%, 50%, 75% and 90% levels to supply 30% crude protein as required by Oreochromis niloticus._All diets were maintained iso-nitrogenous (30% crude protein) and isocaloric (285 Kcal/100g DE, 428.89+ 2.31 Kcal/100g GE) by varying the amount of corn. In a 56 days feeding experiment Oreochromis niloticus fingerlings were fed the diets. The feeding trial was conducted in glass aquaria. Evaluation of growth parameters and nutrient utilization of the fish was based on weight gain, feed conversion ratio, specific growth rate, and protein efficiency ratio and protein productive value. Best growth and nutrient utilization was obtained in fish fed the control diet and it decreased as the soybean level increased in the diet. Cost of diets reduced with inclusion of soybean meal. However, the cost of 1kg gain in body weight of Oreochromis niloticus was lowest on the control diet due to lower feed conversion ratio. Statistic analysis revealed that the soybean inclusion levels in diet is negatively correlated to weight gain and protein gain but has a strong positive correlation with lipid content of the fish carcass.