Dietary supplementation with astaxanthin from hydrolysed shrimp (Penaeus vannamei) by-product: Effect on antioxidant activity and productive response of juvenile Nile tilapia (Oreochromis niloticus)

The aim of this study was to determine the effect of replacing fishmeal with hydrolysed shrimp (Penaeus vannamei) (HS) in the diet of juvenile Nile tilapia (Oreochromis niloticus) under high-density stress situations. Productive parameters, haematological parameters, serum cortisol concentrations and superoxide dismutase (SOD) enzymatic activity were evaluated. In total, 120 tilapias (18.74 g ± 0.11) were allocated in six aquariums (50 L), integrated in a recirculating aquaculture system (RAS) maintaining an equivalent stocking density of 7.2 kg/m³. Two treatments were implemented: T0, with the inclusion of fishmeal and T1, with a total replacement of 100% fishmeal with HS. The study lasted 30 days. T1 had lower productive response (p<0.05) as compared to T0, although a slightly higher survival rate. The cortisol level in T0 was lower (p<0.05) compared to T1 (5.40 and 10.28 ng/ml, respectively). There were no significant differences (p>0.05) in the haematological parameters between treatments. The SOD enzymatic activity was significantly (p<0.05) higher in T1 (218.69 U/ml) compared to T0 (120.71 U/ml). The use of HS did not present adverse effects on the welfare and physiological condition of the fish.