Effects of replacing fish meal and fish oil with plant sources in the diet of rainbow trout (Oncorhynshus mykiss)

The present study was performed to elucidate the probable effects of replacing fish meal and fish oil with plant sources on growth performance، feed utilization indices and muscle fatty acid profile of rainbow trout. Fish with an average weight of 15±2 g were distributed into 12 (300 L) tanks (50 fish/tank) and reared for 60 days using different experimental diets. Fish oil fully replaced with a blend vegetable oil canola: linseed: safflower (40:30: 30، respectively) and fish meal was substituted by plant protein at three different levels of 40، 70، and 100%. The control diet contained fish meal and fish oil as the only sources of dietary protein and lipid. Results showed that replacement of 40% fish meal with plant protein did not have any negative effects on growth indices، feed utilization and proximate composition of trout muscle compared to control diet (P>0. 05). However، replacing 70 and 100% fish meal with plant protein resulted in significantly decreased final weight، feed conversion ratio، protein content of fillets، protein and lipid productive values and protein efficiency ratio (P<0. 05). Fish oil replacement with a vegetable oil blend resulted in significant increment of Vaccenic acid، Linoleic acid and Linolenic acid and significant decrease of Myristic acid، Palmitic acid، Oleic acid، Arachidonic acid، Eicosapentaenoic acid and Docosahexaenoic acid in the fillets (P<0. 05).