Effects of total replacement of dietary fish oil on growth performance and fatty acid compositions of hybrid tilapia ( Oreochromis niloticus × O. aureus )

The aim of this study is to evaluate the effects of total replacement of fish oil (FO) with pork lard (PL), soybean oil (SO), or tea seed oil (TO) on growth and fatty acid compositions of hybrid tilapia ( Oreochromis niloticus × O. aureus ). Four diets were formulated to contain 4.5 % of each of the different lipid sources. Each diet was assigned to triplicate groups of 15 hybrid tilapia with the same initial body weight (4.6 ± 0.5 g). After a 10-week feeding, the FO, SO, and TO groups had similar final body weight. The mean hepatosomatic index in the FO group was significantly lower than the other groups (2.5 vs 2.9–3.0; P < 0.05). Whole-body lipid levels were highest in the TO group (5.2 ± 0.4 %) and lowest in the FO group (4.3 ± 0.5 %). Total n-3 polyunsaturated fatty acids (PUFA) concentrations were greater in the SO and FO groups (5.5 ± 0.1 and 7.1 ± 0.2, respectively) than in the PL and TO groups (1.7 ± 0.1 and 1.4 ± 0.1, respectively). The FO group had a 2- to 4-fold reduction in the n-6/n-3 PUFA ratio relative to the other groups. The concentrations of both docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) were significantly ( P < 0.05) higher in the FO group than in the other groups. Our data demonstrate that total replacement of dietary FO with SO or TO has little effects on growth of hybrid tilapia but reduces the contents of health-benefiting DHA and EPA in fish body.