Nutrition of Atlantic salmon (Salmo salar): The requirement and metabolism of arginine

This experiment was conducted to determine the dietary arginine requirement of medium sized Atlantic salmon (383 +/- 62 g) given a high energy diet (26.1 KJ/g) Zein was used as major protein source in the experimental diets supplemented with synthetic amino acids resembling the amino acid pattern of fish meal, with the exception of arginine. Arginine content was 11.3 (2.7), 16.8 (4.0), 20.2 (4.8), 26.0 (6.2), and 28.6 (6.8) g/kg dietary dry matter (% of dietary protein). Expressed in terms of digestible energy the arginine content was 0.53, 0.78, 0.94, 1.21, and 1.33 g/MJ. Protein content on dry weight was 42% in all diets. Weight gain and protein efficiency parameters were together with increasing levels of urea and ornithine in plasma and free arginine in muscle and plasma used to indicate the requirement of arginine. The growth and protein retention obtained indicated that Atlantic salmon has a requirement of arginine of 21.2-21.6 g/kg dietary dry weight (5.0-5.1% of the protein) or 1.0 g/MJ digestible energy. The metabolic parameters indicated a requirement of 20.2 g/kg dietary dry weight (4.8% of the protein) or 0.94 g/MJ. Increased dietary levels of arginine seemed to interact with the tissue free concentrations of several indispensable amino acids. (C) 1997 Elsevier Science Inc.