Diet digestible energy content affects lysine utilization, but not dietary lysine requirements of rainbow trout ( Oncorhynchus mykiss) for maximum growth

The effect of diet composition on essential amino acid (EAA) utilization and requirements is a topic of some controversy in fish. A growth trial was conducted to examine the effect of diet digestible energy (DE) content on lysine utilization and lysine requirement in rainbow trout ( Oncorhynchus mykiss). Twelve isoproteic (40% digestible protein (DP)) practical wheat-gluten-based diets, with two DE levels (16 and 20 MJ/kg) and six lysine levels (1.2% to 2.5%), were hand fed to near-satiety to triplicate groups of rainbow trout (initial weight 24 g) over 12 weeks. Across dietary lysine levels, higher ( P0.10) of diet DE content on whole body protein deposition. Based on body weight gain, diet DE content did not affect ( P>0.10) lysine requirements, expressed as dietary concentration, while different statistical models yielded different ( P