Author : Thanh Hai Hoang

Summary : This study aimed to assess the replacement of 40% protein of fish meal (in the Control Diet) with soybean meal, corn gluten meal, poultry by-product meal and a mixed protein (in a 1.5:1: 2.5 ratio) in the diets of Asian seabass (Lates calcarifer). Five experimental diets were formulated to meet the about 49% dietary protein of seabass. The control diet contained Danish fish meal as the sole protein source. One hundred fifty fish with initial body weight 4.59+-0.29g were randomly assigned to fifteen rectangular glass aquaria of 451 capacity and fed twice daily for 8 weeks. No water problem was experienced during the experiment, all water parameters were within acceptable range. In comparison with initial lipid content (4.99%), feeding seabass with test diets resulted in high lipid levels (19.69-22.93%) while crude protein increased slightly at the end of experiment. There was a downward trend in ash and moisture contents in the final body of seabass. There were no significant differences between the control diet and the mixed protein diet in terms of percentage weight gain (%WG), specific growth rate (SGR) and protein efficiency ratio (PER). Feeding seabass with the control diet resulted in the significantly lowest FCR compared with those fed other test diets. Seabass fed the poultry by-product diet exhibited the highest FCR and was significantly different from those fed the control diet, soybean diet and mixed protein diets but not from those fed the corn gluten diet. The results did not show any remarkable difference between the control diet and the mixed protein diet on hepatosomatic index (HIS) and viscerasomatic (VSI) of seabass juvenile. Results from the present study demonstrated that the mixed protein diet which replaced 40% fish meal protein could be applied to feed to juvenile seabass without adverse effects on growth, body composition and it was also nutritionally adequate and economical.