Effect of past nutritional history and fasting on feed intake and growth in rainbow trout Oncorhynchus mykiss

Groups of juvenile rainbow trout were fed to satiation for 10 days after 1, 11 and 21 days of feed deprivation. These fish (initial body weight =20 +/- 2 g) were previously fed at different feeding levels (0.5 or 1.5% initial body weight, to satiation) with a high (20.4 kJ . g(-1)) or a low (16.2 kJ.g(-1)) digestible energy diet content for 34 days. It is shown that past nutritional history affected growth performance: duration of feed deprivation has a major effect on intake and feed conversion efficiency; previous feeding level has an effect on intake; dietary energy content affected feed conversion efficiency. In addition, an attempt was made to identify some of the metabolic parameters that could be involved in the increase in growth performance during the 10-day feeding period (whole body and muscle protein and lipid, plasma glucose, free fatty acids and triglycerids). Feed intake after fasting does not appear to be driven by body composition but feed conversion efficiency was correlated with the plasma glucose and free fatty acids. (C) 2000 Ifremer/Cnrs/Inra/Ird/Cemagref/Editions scientifiques et medicales Elsevier SAS.