Document Type : Research Paper
Fisheries Department, Faculty of Natural Resources, University of Guilan, Sowmeh Sara, Guilan, Iran
The aim of this study was to compare the effect of high and low levels of dietary fat on growth performance and chemical composition of carcass in juvenile rainbow trout (Oncorhynchus mykiss). One hundred and eighty juvenile rainbow trout (with mean weight and total length 25.95 ± 2.9 g and 13.27 ± 2.1 cm, respectively) were distributed in 6 tanks (30 fish per tank). Two experimental diets with equal amounts of protein and different levels of fat (10% fat as the low level and 20% as high) were formulated. The fish was fed three times a day manually to satiation during the 8-week experiment. Fish fed with diets containing 20% fat showed higher weight gain and specific growth rate (P<0.05), but FCR showed no significant difference between the two treatments. Analysis of fish body chemical composition showed no significant difference between treatments in fat, protein and ash composition (P>0.05). In general, increased levels of fat in the diet of juvenile rainbow trout showed positive effects on growth indices when compared to the low-fat treated fish.