Effect of feeding time on digestibility, growth performance and protein metabolism in the rainbow trout Oncorhynchus mykiss: interactions with dietary fat levels

The effect of feeding time was studied in rainbow trout fed different dieta ry levels of fat. Fish were fed either 1 h after light on in the morning or 1 h after light off in the evening with a low energy diet (LE, 6 % lipid) or a high energy diet (HE, 23 % lipid). Regardless of the diet, apparent di gestibility and post prandial protein synthesis were higher in fish fed in the morning than in those fed at the beginning of the night. In fish fed th e LE diet in the morning, growth performance and nutrient retention efficie ncy tended to be higher than in those fed at the beginning of the night. In contrast, fish fed the HE diet in the morning had lower protein growth rat e, protein content and protein retention efficiency than those fed in the e vening. These results suggest that protein metabolism might be involved in the effect of feeding time on growth and that there is an interaction betwe en the time of feeding and dietary level of fat on growth. (C) 2000 Ifremer /Cnrs/Inra/Ird/Cemagref/Editions scientifiques et medicales Elsevier SAS.