Use of Amazonian Mauritia flexuosa fruit pulp as chemoprotectant against ammonia and nitrite toxicity to juvenile shrimps Litopenaeus vannamei

This study investigated the effects of the ammonia and nitrite toxicity in shrimp <i>Litopenaeus vannamei </i>juveniles fed diets containing Amazonian <i>Mauritia flexuosa</i> fruit pulp. The post-larvae (PL) shrimps (weight 5.0 ± 0.3 mg) were fed with five diets (36% protein, 10% lipid), containing 0 (Control group), 1.25, 2.50, 5.00, and 10.00% (W/W) of <i>M. flexuosa</i> fruit pulp inclusion (1 shrimp L^-1, tank of 100 L, treatments in triplicate) for 43 days. After this period, the juvenile shrimps (weight 396.00 ± 0.35 mg) were randomly distributed among 30 tanks with 30 L of useful volume, containing 20 shrimps per tank and exposed (96 h) to ammonia (0.48 mg NH₃-N L^-1) and nitrite (40 mg NO₃ L^-1) toxicity, in triplicate. Measured variables were the total antioxidant capacity (ACAP), lipid peroxidation (TBARS), reduced glutathione (GSH) levels and concentration of protein sulfhydryl groups (P-SH). The results indicated a significant increase (<i>p</i>&lt;0.05) in ACAP, when shrimps were fed 2.50 and 5.00% (ammonia exposure), or 5.00 and 10.00% (nitrite exposure) of <i>M. flexuosa</i> inclusion. Similarly, lipid peroxidation levels were lower (<i>p</i>&lt;0.05) in shrimps exposed to ammonia or nitrite and fed the inclusion of 2.50-10.00% of <i>M. flexuosa</i> in the diet. The GSH levels increased (<i>p</i>&lt;0.05) in shrimps that were exposed to ammonia and fed 10% of <i>M. flexuosa</i>. However, there was no significant difference (<i>p</i>&gt;0.05) in the P-SH levels, after both ammonia and nitrite exposure. It was concluded that the use of <i>Mauritia flexuosa</i> improves the resilience of <i>Litopenaeus vannamei</i> to cope with ammonia and nitrite toxicity and indicates its use as a chemoprotectant against toxic nitrogenous compounds. Particularly, the conspicuous TBARS reduction after nitrite exposure and augmented GSH levels in ammonia-exposed shrimps previously supplemented with <i>M. flexuosa </i>fruit pulp suggest a hormetic response.