Dietary sodium alginate effect on growth, digestion, body composition, antioxidant capacity, and mucous immune response in yellowfin sea bream Acanthopagrus latus

Abstract In the present study, the effects of dietary supplementation of low molecular weight sodium alginate on growth, body composition, antioxidant enzymes, digestive enzymes, and immune response in yellowfin sea bream juvenile (Acanthopagrus latus) were investigated. Fish (n=180) were divided into 3 groups with 3 replicates and received dietary treatments including basal diet without sodium alginate (control treatment), basal diet containing 5 g sodium alginate per kg diet (0.5% treatment), and 10 g sodium alginate per kg diet (1% treatment) for 8 weeks. The results showed that the final weight, weight gain, specific growth rate, condition factor, feed conversion, and protein efficiency ratios did not reveal a significant improvement compared to the control treatment (P>0.05). The obtained results indicated that dietary sodium alginate did not affect body composition (P>0.05). The activity of antioxidant enzymes superoxide dismutase (SOD) and catalase (CAT) in the groups fed on 0.5 and 1% sodium alginate showed a significant increase (P<0.05) compared to the control group. But, the activity of lipid peroxidation (MDA) in the groups fed on 0.5 and 1% sodium alginate showed a significant decrease (P<0.05) compared to the control group. The digestive enzymes increased significantly (P<0.05) by supplementation of sodium alginate, compared to the control group. Mucus lysozyme and complement activity were not significantly different (P>0.05). Overall, it can be concluded that feeding of yellowfin sea bream on the diet supplemented with 0.5 and 1 percent sodium alginate for a period of 8 weeks do not enhance the non-specific immune response and growth. Nonetheless, sodium alginate improved the activity of the antioxidant and digestive enzymes, indicating the positive effects of sodium alginate on enzymatic responses.