Incorporation and fatty acid composition in liver of Nile tilapia fed with flaxseed oil

ABSTRACT. One of the most consumed freshwater fish in South America is Nile tilapia. The present study examined the effects of flaxseed oil (FO), source of alfa-linolenic acid (LNA), on the total lipid composition and polyunsaturated fatty acid, n-6 and n-3 PUFA, contents on Nile tilapia (Oreochromis niloticus) liver. Tilapias were given diets with increasing levels 0.00, 1.2, 2.50, 3.75 and 5.00 % (w w-1) of FO as a replacement of sunflower oil for five months. Fatty acids analysis of methyl esters revealed 45 fatty acids common to all treatments. The increase of flaxseed oil resulted in a decrease in total n-6 PUFA (35.1 to 21.1%) and an increase in n-3 PUFA (3.3 to 18.5%). The diet with LNA underwent sequential desaturation and elongation in liver, leading to an increase in all n-3 PUFA and a decrease in n-6/n-3 ratios (10.7 to 1.1). The manipulation of fatty acids with FO may be used to increase n-3 PUFA and to help balance n-6/n-3 PUFA in dietary supplements, thus, the liver tilapia becomes one product with major nutritional value