Inclusion of açaí in the shrimp diet Litopenaeus vannamei(Boone, 1931) carried out in a biofloc system: Effects on modulating the toxicity of nodularin cyanotoxin
The experiment considered the inclusion of 10% of açaí Euterpe olaracea in the diet of shrimp Litopenaeus vannamei, besides the control diet, without açaí. The feed was given twice a day for 30 days and, afterward, the shrimps were subdivided into another 3 treatments (Control, 0.25 and 1 μg/L of hepatotoxin nodularin), both in the group that received inclusion with açaí and those fed with the control diet. At the end of the experiment, it was evaluated the concentration of reduced glutathione (GSH), sulfhydryl groups associated with proteins (P-SH), lipid peroxidation (TBARS method), the activity of glutathione-S-transferase (GST) in muscle, hepatopâncreas and gills, and nodularin accumulation in muscle. The inclusion of açaí in the diet was able to increase the levels of GSH in the hepatopancreas and gills and to decrease the levels of lipid peroxidation in the muscle of nodularin-exposed shrimps in respect to the control group. Nodularin exposure did not affect P-SH levels in the analyzed organs, although açaí treatment reduced P-SH levels in muscle. TBARS muscle concentration was reduced in shrimps fed with açaí and exposed to nodularin. Finally, nodularin exposure was not followed by toxin accumulation in muscle but, notably, it was detected measurable levels in control groups (fed or not with açai). In general, the results showed that açaí was able to infuse the antioxidant effects of shrimp, and it was also able to reduce the levels of TBARS in the muscle when exposed to nodularina, suggesting the use of açaí as chemoprotector.