Effect of dietary flaxseed oil level on the growth performance and fatty acid composition of fingerlings of rainbow trout, Oncorhynchus mykiss

Masiha et al. SpringerPlus 2013, 2:1

Abstract:

This study evaluated the suitability of flaxseed oil as a source of supplemental dietary lipid for fingerlings of
rainbow trout (Oncorhynchus mykiss). Triplicate groups of the 30 fingerlings held under identical culture conditions
were fed twice daily by iso-nitrogenous, iso-calorific and iso-lipidic diets for 8 weeks. Experimental diets consisted of
30.2% protein, 18.6 kJ g-1 energy and 16.5% lipid from fish oil (FO), flaxseed oil (FxO) and 1:1 blends of the oils
(FFxO). Moisture, ash, protein, final body weight, specific growth rate, weight gain, feed conversion ratio, survival
and hepatosomatic index were not affected by treatments but the percent of lipids was significantly highest in fish
fed the flaxseed oil diet (FxOD). The condition factors of fingerlings reared on FxOD and fish and flaxseed oils diet
(FFxOD) were significantly lower than those fed the fish oil diet (FOD). Protein efficiency ratio (PER) was significantly
higher than those fed the FOD and FFxOD. Whole body fatty acid compositions mirrored those of diet treatments.
The highest amounts of highly unsaturated fatty acids (HUFAs) were detected in fish fed 100% FO, which was
significantly different from other treatments. In all treatments polyunsaturated fatty acids/saturated fatty acids
(PUFAs/SFAs) and n-6/n-3 ratios were higher than 0.45 and lower than 4, respectively. Present results indicate the
fingerlings can be reared on diets in which FO has been replaced with FxO, with no significant effects on fish
performance.