Effect of Replacement of Fish Oil by Grape Seed Oil on Growth Indices and Protease Enzymes Activity in Oncorhynchus mykiss

Aims: Increasing the aquatic consumption, developing aquaculture, and the need for aquatic food production will make unclear the availability to fish oil in the future. The aim of this study was to investigate the effect of replacement of fish oil by grape seed oil on growth indices and protease enzymes activity in Rainbow Trout.
This study was conducted on 450 Rainbow Trout during a 60-day period. In this study, control diet (A) containing 100% fish oil and 25% (B), 50% (C), 75% (D), and 100% (E) grape seed oil were used instead of fish oil. The data were analyzed by Graph pad prism and SPSS 20 software, using one-way ANOVA test.
Findings: The highest final weight and weight gain was in diet C and the lowest was in D, having a significant difference. Specific Growth Rate (SGR) and Protein Efficiency Ratio (PER) had no significant difference. The highest and lowest feed conversion ratio (FCR) was observed in diets E and C, respectively, with a significant difference. The highest fat efficiency was in diet C. The highest feed efficiency was in diets C and D and the lowest was in E, and the diets were not significantly different. The most activity of pepsin and trypsin was observed in pyloric additions in diet C and in intestine in C and D. The optimal amount of fish oil replacement was satisfied by grape seed oil 50% (diet C).
The diet containing 50% fish oil and 50% grape seed oil is effective in improving the growth indices and activity of pepsin and trypsin enzymes in Rainbow Trout.