Growth and feeding responses of the mutton snapper, Lutjanus analis (Cuvier 1828), fed on diets with soy protein concentrate in replacement of Anchovy fish meal

Abstract

feeding responses (second phase) of juvenile mutton snapper fed four isonitrogenous and isoenergetic diets with increasing levels of soy protein concentrate (SPC) in substitution to ¢sh meal (FM). The FM was replaced by SPC at 0% (basal diet, SPC000), 33% (SPC130), 57% (SPC214) and 77% (SPC300). After 95 days of rearing, ¢sh fed SPC300 attained a signi¢- cantly lower body weight (54.9 13.2 g) compared with those fed diets SPC000, SPC130 and SPC214 (76.5 14.0 g, 73.9 13.8 g and 70.5 14.0 g respectively). Fish yield increased signi¢cantly from 891 36 g m 3 for ¢sh fed SPC300 to an average of 1099 111g m 3 for other diets. A maximum ¢sh body weight gain of 0.60 0.05 g day 1 and a maximum speci¢c growth rate of 1.47 0.07% day 1 were achieved for SPC000. Behavioural assays conducted during10 days revealed the loss in ¢sh growth with diets containing higher levels of SPC was due to a decline in feed intake. Low feed intake driven by a poor feed palatability appeared to have been a major obstacle against higher inputs of SPC in diets for mutton snapper.