Supplementation of coated and uncoated crystalline amino acid mix in formulating a low‐fishmeal diet for Penaeus monodon (Fabricius, 1798): Effect on growth, digestibility, body composition, haemolymph indices and nitrogen metabolism

A sixty‐day feeding trial was conducted to elucidate the effect of coated and uncoated crystalline amino acid mix (CAA) in Penaeus monodon . The control diet (CNT) was formulated with 250 g/kg fishmeal, and three more test diets were prepared by replacing 50% (125 g/kg) of fishmeal (w/w) using a blend of plant proteins with no supplementation of CAA (AA‐NL), supplementation of uncoated (AA‐NC) and coated (AA‐CT) CAA. The AA‐CT diet showed ( p  < .05) lower leaching of amino acids (1.13%) than other diets (2.78%–3.04%). DGC was high ( p  < .05) in shrimp fed on CNT and AA‐CT (1.48%–1.49%/day) than other groups (1.32%–1.37%/day). Of all the treatments, FCR was poor ( p  < .05) in AA‐NL (2.25). The dietary treatments did not influence survival ( p  = .841) and whole‐body composition. The peak of free amino acid was synchronized (60 min) between AA‐CT and CNT groups. The control group showed a higher nitrogen intake, oxygen consumption and O:N ratio and lower ammonia‐N excretion. Haemolymph indices varied ( p  < .05) among the dietary groups. As a result of the N‐metabolism study, the experimental diets were ranked as CNT>AA‐CT>AA‐NC. In conclusion, a blend of CAA could be effective in formulating low‐fishmeal diets and could replace 50% (125 g/kg) of dietary fishmeal using a plant protein mix in P .  monodon .