Effect of dietary vegetable oils on the growth performance and fatty acid composition of fingerlings of rainbow trout,oncorhynchus mykiss
This study evaluated the suitability of canola and flaxseed oils as source of supplemental dietary lipid for fingerlings of rainbow trout. Triplicate groups of the 30 fingerlings were fed twice daily by iso-nitrogenous, and iso-calorific diets for 8 weeks. Experimental diets consisted of 30.2% protein, 18.6 kJ/g energy and 16.6% lipid from fish oil, canola oil, flaxseed oil, 1:1 blends of fish and canola oils, 1:1 blends of fish and flaxseed oils, 1:1 blends of canola and flaxseed oils and 1:1:1 blends of fish, canola and flaxseed oils. Protein and lipid was significantly highest in fish fed the fish and canola oils diet. Condition factor of fingerlings reared on fish oil diet were significantly higher than other treatments. Protein efficiency ratio (PER) was significantly higher in fish fed the flaxseed oil diet and canola and flaxseed oils diet. The results of fatty acid profile revealed that flesh fatty acid composition is effected by dietary fatty acid composition. The highest amounts of HUFA n-3 were detected in fish fed fish oil diet, which was significantly different from other treatments. Present results indicate the fingerlings can be reared on diets in which fish oil has been replaced with canola and flaxseed oils.