DEFATTED AND FULL-FAT SOYBEAN-MEAL AS PARTIAL REPLACEMENTS FOR FISH-MEAL IN TILAPIA (OREOCHROMIS-NILOTICUS X O-AUREUS) DIETS AT LOW PROTEIN LEVEL

In a previous study, defatted soybean meal was used successfully to partially replace fishmeal in a tilapia diet containing a low level of protein. In this study we assessed the feasibility of partially replacing fishmeal protein with protein from either defatted soybean meal or full-fat soybean meal. The control diet contained blue whiting fishmeal imported from Norway as the sole source of protein. Each test diet contained 24% protein and 11% lipid on an air-dry basis. The diets were isocaloric, containing 395 kcal/100 g diet. Each diet was fed to three groups of fish. The experiment was carried out in a closed rearing system with recirculated filtered water for 9 weeks. The weight gain (%), feed conversion ratio (FCR), protein efficiency ratio (PER) and protein digestibility for fish fed diets in which 30% of fishmeal protein was replaced by defatted soybean meal or by full-fat soybean meal were not significantly (P>0.05) different from those of fish fed the control diet. These data suggest that either defatted soybean meal or full-fat soybean meal can be used to replace 30% fishmeal protein in a diet for Oreochromis niloticus×O. aureus fingerling hybrids when the dietary protein level is low (24%), at least for the first 9 weeks of feeding. Further study of the replacement value of soybean meal protein for fishmeal protein is necessary for the subsequent grow-out stage of tilapia. © 1990.