High DHA algae meal as cost-effective alternative to high DHA fish oil in finisher feed for sobaity sea bream (Sparidentex hasta)

This study evaluated the effects of high DHA algae meal (AlgaPrimeTM DHA) as cost-effective substitute for high DHA fish oil in finisher feeds on growth performance and nutritional quality of sobaity (Sparidentex hasta) muscle. The amount of docosahexaenoic acid (DHA) in finisher feeds were fixed at 9.34% DHA (i.e 0.1.82 g DHA 100-1 g feed), a level equivalent to a commercial finisher feed (Focus Omega 3 P, Skretting, Italy). Two experimental finisher diets (Diets 2 and 3) were prepared by adding high DHA fish oil and high DHA algae meal, respectively into a basal diet (Optibream 3 P, Skretting, Italy) which was used as grow out diet (Diet 1). A commercial finisher feed (Focus Omega 3 P, Skretting, Italy) was used as Diet 4. Each treatment had three replicates in a randomized block design. Fish in all treatments were fed with the same growout feed from the beginning for 3 month and then, three treatment received finisher feeds for another 2 months. All finisher feed treatments resulted in significantly (P < 0.05) better growth performance, feed utilization and higher tissue eicosapentaenoic acid (EPA) and DHA content compared to those receiving the grow-out feed (Diet 1). No significant (P > 0.05) differences were observed between growth and muscle DHA and EPA levels of fish receiving fish oil (Diet 2) and high DHA algae meal (Diet 3)-based finisher feeds. The muscle DHA levels of fish in finisher diets 2 and 3 were also higher (P < 0.05) than those receiving commercial finisher diet (Diet 4). Muscle DHA and EPA in fish receiving finisher feeds were also higher than those of wild sobaity muscle. No significant (P > 0.05) differences were observed between muscle sensory attributes of wild and cultured sobaity. The inclusion of high DHA algae meal at 7% level in the finisher diet also enhanced the non-immunity factors like lysozyme and phagocytic activity of fish. Compared to the grow-out diet, both high DHA algae meal and fish oil diets showed significant elevated levels of immune gene expression for interleukin and superoxide dismutase. The results of the present study demonstrated that high DHA algae meal can be a cost-effective alternative to high DHA fish oil in finisher feeds for sobaity bream.

Automated summary

This study evaluated the effects of replacing high DHA fish oil with cost-effective high DHA algae meal in finisher feeds for sobaity bream. The results showed no significant differences between the growth performance, nutritional quality, and immune gene expression of fish receiving high DHA algae meal and fish oil-based finisher feeds. Therefore, high DHA algae meal can be a cost-effective alternative to high DHA fish oil in finisher feeds for sobaity bream.