Utilization of several plant proteins by gibel carp (Carassius auratus gibelio)

Six isonitrogenous (gross protein content 35%) and isoenergetic (gross ener gy content 17 kJ g(-1)) diets were formulated to investigate the effects of inclusion of plant proteins on the gibel carp (Carassius auratus gibelio L .). The plant proteins tested were: soybean cake (SBC), potato protein conc entrate (PPC), peanut cake (PNC), cottonseed cake (CSC) and rapeseed cake ( RSC). Fish meal (FM) was used as control. In each diet, 27% of the protein was supplied by fish meal, and the rest supplied by the plant protein teste d. Each diet was fed to three groups of gibel carp for 8 weeks in a recircu lation system. Specific growth rate (SGR) in fish fed the control diet was significantly higher than those in the other groups, and SGR in fish fed th e PPC was significantly lower than in fish fed other plant proteins. There was no significant difference in SGR among the other groups. Feeding rates were ranked in the order: RSC > CSC > FM > PNC > SBC > PPC. Conversion effi ciency was highest in groups fed FM, SBC and PNC, followed by groups fed CS C and RSC, and was lowest in the group fed PPC. The fish fed PPC showed low er protein retention than those fed FM and SBC. FM showed highest energy re tention while PPC showed lowest, There was no significant relationship betw een SGR and intake of digestible protein (g g(-1) day(-1)), digestible lysi ne (g g(-1) day(-1)), digestible methionine (g g(-1) day(-1)) or digestible total essential amino acids (g g(-1) day(-1)), suggesting that the differe nces in SGR could not alone account for any of these variables.