Meat and Bone Meal as Partial Substitute for Fish Meal in Nursery Diet for Giant Freshwater Prawn, Macrobrachium rosenbergii (de Man)

An experiment was conducted for 60 d in a recirculatory system consisting of 20 glass aquariums (each of size 41 × 41 × 46 cm) to evaluate meat and bone meal (MBM) as partial replacement for fish meal (FM) in Macrobrachium rosenbergii postlarvae (PLs) with a view to develop an inexpensive nursery diet. Three nursery diets were formulated to contain 32% protein and to be as isoenergetic as possible. FM in these diets was progressively replaced with MBM (Diet 1 contained 25% FM and 14% MBM, Diet 2 contained 20% FM and 20% MBM, and Diet 3 contained 15% FM and 26% MBM). Inclusion levels of mustard oilcake and sesame meal in diets were kept fixed at 10%. A commercial shrimp nursery diet (30% protein) from Saudi Bangla Fish Feed Ltd., Mymensingh, was used as the reference diet (Diet 4). Each treatment had three replicates. PLs of M. rosenbergii (26 ± 0.02 mg) were stocked at the rate of 60 PLs (1 PL/L) in each aquarium. At the beginning, PLs were fed three times daily at a rate of 20% of the body weight and it was gradually reduced to 10% at Day 30. The ranges of water quality parameters in the system were as follows: temperature, 27–29 C; dissolved oxygen, 6.5–8.4 mg/L; pH, 6.8–8.3; and total ammonia, 0.01–0.15 mg/L. The result of the study showed that there was no significant difference ( P  > 0.05) between the weight gains of PLs fed Diet 1 (containing 14% MBM) and Diet 4 (reference diet) but was significantly higher than other dietary groups containing higher levels of MBM. Diets 1 and 4 showed significantly lower ( P  < 0.05) apparent food conversion ratios (1.74 and 1.73, respectively). The survival (%) of PLs ranged between 62 and 76% with PLs fed Diets 1 and 4 showing significantly higher ( P  < 0.05) survival. The result of the study demonstrated that the MBM could be included at 14% level in a nursery diet, and a diet containing 25% FM, 14% MBM, 10% sesame meal, and 10% mustard oilcake may be recommended for profitable production of PLs of M. rosenbergii .