Assessment of requirement values for essential amino acids in the prawn, Marsupenaeus japonicus (Bate) S Teshima, M S Alam, S Koshio, M Ishikawa & A Kanazawa Laboratory of Aquatic Animal Nutrition, Faculty of Fisheries, Kagoshima University, Japan Correspondence: S Teshima, Faculty of Fisheries, Kagoshima University, 4-50-20 Shimoarata, Kagoshima, 890-0056 Japan. E-mail: teshima@fish.kagoshima-u.ac.jp Abstract The requirements of juvenile prawn, Marsupenaeus japonicus (Bate), 0.79 g initial body weight, for essential amino acids (EAA) were evaluated based on the daily increase of each EAA in the whole body when the prawn was maintained on a diet with a high nutritive value (a casein-squid protein- based diet). The quantities of each EAA needed daily for growth and maintenance of prawn are conceived to correspond to the daily requirements of this prawn species for EAA. Therefore, these requirement values of respective EAA should be supplied from dietary proteins. To determine these values, protein and amino acids of the whole body of the prawn were quantified before and after feeding experiments, and the quantities of respective EAA needed to meet the requirements were estimated based on the EAA profile of the whole body protein of prawn. As a result, the con- tents of EAA in dietary proteins (%) needed to meet the requirements of the prawn for EAA were assessed to be: threonine (2.3), methionine (1.3), valine (2.4), isoleucine (2.3), leucine (3.4), phenyl- alanine (2.6), lysine (3.2), histidine (1.1), arginine (2.9) and tryptophan (0.6), respectively, when the prawn are fed 50% protein diet with 90% pro- tein digestibility at a ration size of 2% (% of body weight). Keywords: prawn, Marsupenaeus japonicus, amino acid, requirements, retention Introduction The nutritive value of dietary protein for animals is primarily based on the amino acid composition and digestibility (Wilson & Poe 1985). Although shrimp or prawn such as Palaemon serratus (Pennant) (Cowey & Forster 1971), Penaeus aztecus (Ives) (Shewbart, Meis & Ludwig 1972) and Marsupenaeus japonicus (Bate) (Kanazawa & Teshima 1981) re- quire the same 10 essential amino acids (EAA) as do fish, little information is available for quantitative requirements of shrimp for EAA. To quantify the amino acid requirements of fish, it is a common practice to rear the fish with diets containing graded levels of supplemental EAA to be tested for growth performance. Attempts to replace dietary protein with crystalline amino acids for investigating quan- titative EAA requirements of shrimp have been un- successful due to leaching from the diet (Pascual 1989) and/or poor utilization of lower molecular weights of nitrogen compounds such as amino acids as protein sources (Deshimaru & Kuroki 1974; Deshimaru & Kuroki 1975; Deshimaru 1981). Several workers have investigated the quantita- tive requirements of shrimp such as Penaeus mono- don (Fabricus) (Chen, Len & Roelants 1992; Millamena, Bautista-Teruel & Kanazawa 1996a, b; Millamena, Bautista, Reyes & Kanazawa 1997; Millamena, Bautista, Reyes & Kanazawa 1998) and Litopenaeus. vannamei (Boone) (Fox, Lawrence & Li-Chan 1995) for several EAA by reducing the leaching losses of crystalline amino acids from test Aquaculture Research, 2002, 33, 395±402 ß 2002 Blackwell Science Ltd 395