Effect of Substituting De-hulled or Fermented Soybean Meal for Fish Meal in Diets on Growth of Hybrid Tilapia, Oreochromis niloticus×O. aureus

Two feeding experiments were conducted to evaluate the effects of replacing fish meal with de-hulled soybean meal (DSBM) and fermented soybean meal (FSBM) in diets on growth of juvenile hybrid tilapia. In experiment I, four isonitrogenous and isocaloric diets were formulated to contain 0-20% fish meal (or 57-31.6% DSBM) and fed to juvenile hybrid tilapia of 0.38 g initial body weight for 8 weeks. In experiment II, the diets containing 0-20% fish meal (51-28.3% FSBM) were fed to juvenile hybrid tilapia of 0.34 g. In both trials, the percent weight gain (WG) of the fish fed control diet (fish meal-free) was significantly (P＜0.05) lower than those fed diets containing fish meal. No difference was found in WG among fish fed diets containing fish meal. Although there was no significant (P＞0.05) difference among test groups, feed conversion and protein efficiency ratio followed similar trends as WG. Addition of encapsulated methionine did not improve the growth of fish fed diets containing no fish meal. Lowest feed consumption in control, indicating poor palatability from lacking the attraction of fish meal, could be the main reason for low WG of this group of fish.