Effects of dietary n-3 highly unsaturated fatty acids on growth, non-specific immunity, expression of some immune-related genes and resistance to Vibrio harveyi in hybrid grouper (♀ Epinephelus fuscoguttatus × ♂ Epinephelus lanceolatu)

This study was conducted to investigate the effects of dietary n-3 highly unsaturated fatty acids (n-3 HUFA) on growth performance, non-specific immunity, expression of some immune-related genes and resistance to Vibrio harveyi in juvenile hybrid grouper (♀ Epinephelus fuscoguttatus × ♂ Epinephelus lanceolatu). Six isoproteic and isolipidic experimental diets were formulated with graded levels of n-3 HUFA (0.65, 1.00, 1.35, 1.70, 2.05 and 2.40% of dry matter, respectively), and the 0.65% group was used as control group. Each diet was randomly allocated to triplicate groups of fish in 1000 L fiberglass tank, and each tank was stocked with 40 fish (initial weight 12.06 ± 0.01 g) for 8 weeks. Results showed that feed conversion ratio (FCR), survival rate (SR), hepatosomatic index (HSI) and condition factor (CF) were all not significantly affected by dietary n-3 HUFA levels (P > 0.05). Weight gain (WG) and specific growth rate (SGR) in 1.35% group were significantly higher than those in 2.40% group (P < 0.05). Crude lipid of body in 1.00% group was significantly lower than that in 1.70% and 2.40% groups (P < 0.05). Liver and muscle fatty acid profiles reflected that of diets. Before challenge with Vibrio harveyi, the activity of serum superoxide dismutase (SOD), catalase (CAT) and content of complement 3 (C3) in 1.35% and 1.70% groups significantly higher than those of control group (P < 0.05). After challenge with Vibrio harveyi, ser...
Source: Fish and Shellfish Immunology - Category: Biology Source Type: research