Effects of replacing fish meal with plant protein on growth performance, feed utilization and muscle fatty acid profile of rainbow trout (Oncorhynshus mykiss)

The present study was performed to elucidate the probable effects of higher levels of replacing fish meal with plant protein on growth performance, feed utilization indices and muscle fatty acid profile of rainbow trout. 700 fish with average weight of 15±2g were distributed into 12 (300L) tanks (50 fish/tank) and cultured for 60 days using experimental diets. Fish meal was substituted by plant protein at three levels of 40, 70, and 100% along with a control diet. Results showed that 40% fish meal replacement with plant protein did not have negative effects on growth indices (final weight: 69.0±2.0g, feed utilization and muscle proximate composition compared to control group (final weight: 71.1±2.0g). However, replacing fish meal with 70% and 100% plant protein showed significantly decreased in final weight 56.9±1.0 and 47.9±3.0 grams, respectively, feed conversion ratio, protein content of fillets, protein and lipid productive values and protein efficiency ratio (P<0.05). Higher fish meal replacement with plant protein concomitantly resulted in significant increase of C18:2n-6 and C18:3n-3 in fillets compared to fish fed with control diet (P<0.05).