Two filamentous microalgae as feed ingredients improved flesh quality and enhanced antioxidant capacity and immunity of the gibel carp (Carassius auratus gibelio)

A 40-day experiment was conducted to investigate the effects of two filamentous microalgae as feed ingredients on growth performance, tissue fatty acid profiles, pigmentation and immunity of gibel carp (204.83 +/- 2.17 g, mean +/- SD). Three diets (control, Oedocladium sp. and Tribonema sp.) were formulated. In the control diet, no microalgal meal was added and into the Oedocladium and Tribonema diets were added 40 g/kg Oedocladium sp. meal and 50 g/kg Tribonema sp. meal, respectively. Compared to the control, the addition of Oedocladium sp. and Tribonema sp. had significant effects on tissue fatty acid profiles, antioxidant capacity and immunity without compromising growth, body composition and pigmentation. The addition of Tribonema sp. and Oedocladium sp. significantly increased the EPA, DHA profiles and the ratio of n-3/n-6 polyunsaturated fatty acids, and simultaneously decreased the n-6 polyunsaturated fatty acids profile in fish muscles. Moreover, addition of Tribonema sp. to the diet significantly increased muscle palmitoleic profile and EPA + DHA contents. Furthermore, the addition of either microalga significantly increased the total superoxide dismutase activity level and the complement 3 and immunoglobulin M contents in the plasma. These results demonstrate that Oedocladium sp. and Tribonema sp. can be used as feed ingredients to improve flesh quality and increase the immunity of fish.