A 60 days feeding trial was conducted to investigate partial replacement of fishmeal (FM) with either soybean meal (SBM) or distillers dried grain solubles (DDGS) as alternative protein sources for milkfish, Chanos chanos fingerlings. Nine experimental diets were formulated with either fishmeal or with two alternative protein sources such as SBM or DDGS at three protein levels (35, 40 and 45%). Milkfish fingerlings (270 nos.) with mean length and weight of 5.24±0.03 cm, 1.25±0.05 g were selected for the study and in total there were 9 treatments in triplicates. The experimental diets were: F35 (35% CP - FM diet), F40 (40% CP - FM), F45 (45% CP - FM), FS35 (35% CP - FM + SBM), FS40 (40% CP - FM + SBM), FS45 (45% CP - FM + SBM), FD35 (35% CP - FM + DDGS), FD40 (40% CP - FM + DDGS), FD45 (45% CP - FM + DDGS). Diets incorporated with fishmeal alone served as control diet for this experiment. We observed that, final weight was significantly (p<0.05) higher for fishmeal based diet irrespective of the crude protein level. The same trend was observed for body weight gain for FM based diet. Specific growth rate (SGR) was found to be more than 2% per day for all the experimental diets fed fish and FD45 showed the lowest SGR compared to other treatment groups. Similarly FD45 had poor feed conversion ratio (FCR) when compared to other dietary groups. Survival rate of the fingerlings was found to be significantly higher for all FM diets (80%), FS35 (80%) and FD35 (80%) diet fed groups, whereas FD45 dietary group showed significantly lower survival rate (60%). Higher amylase activity was observed in F40 diet, higher lipase enzyme activity in FS 35 diet, while higher protease activity was recorded in F35 diet and the values showed significant difference (p<0.05) between different treatment groups. Results of the study, clearly indicate that soybean meal (FS35) could be used to partially replace the fishmeal in the diet of milkfish fingerlings.
The Substitution of soybean meal by fermented tofu dregs in the milkfish (Chanos chanos) diet