Optimization of flaxseed oil feeding time length in adult Nile tilapia (Oreochromis niloticus) as a function of muscle omega‐3 fatty acids composition

This study evaluated the omega-3 (n-3) fatty acids and the proximate composition of muscle tissue of adult Nile tilapias to select the best feeding time length with a diet containing 70 (g kg−1 wt) flaxseed oil (FO). The results showed that dietary complementation with FO for 45 days is suitable for obtaining high levels of protein (164 g kg−1), total lipids (94 g kg−1), and ash (18 g kg−1). Furthermore, there was a significant difference (P < 0.05) in the reduction of n-6 and an increase in the concentration of n-3. With 45 days’ time of FO feeding, fish weight was 532 g and it was improved by the incorporation of total n-3 (9.8%), consisting of alpha-linolenic acid (LNA; 6.3%), and n-3 very long-chain polyunsaturated fatty acid (n-3 VLC-PUFA; 3.5%), and including docosahexaenoic acid (DHA; 1.2%). This gave a better n-6/n-3 ratio (1.1) of muscle tissue, a more desirable ratio than the present ratio sometimes as high as 1 : 20 in human diets. The concentrations of n-3 VLC-PUFA were higher than those of native Brazilian freshwater fish. Thus, 45 days is the shortest time period required for the inclusion of FO oil in tilapia feed to raise the nutritional value of adult Nile tilapia.