Capacidade antioxidante em Oreochromis niloticus (Cuvier, 1829) submetidos a dieta com resíduo de maracujá em sistema de recirculação de água com alfaces

Abstract

The study aimed to evaluate the effect of inclusion of passion fruit residue in the Nile tilapia diet, in a recirculation system (RWS), with the aid of lettuce for water treatment. The study was conducted in 12 polyethylene tanks with a volume of 150 L, for 60 days, distributed in a completely randomized design with four treatments: T1= 12% inclusion of passion fruit residue (PFR) with lettuce, T2= inclusion of 12% PFR, without lettuce, T3= 0% inclusion of PFR with lettuce, and T4= 0% inclusion of PFR without lettuce, and 3 repetitions. The experimental units contained a stocking density of 25 juveniles (3.75 ± 0.40 g and 5.84 ± 0.50 cm). There were no significant differences in fish performance parameters for the treatments evaluated. The units with lettuce showed significant differences in ammonia concentrations compared to treatments without lettuce. Regarding antioxidant capacity, there was a significant difference (p<0.05) in the activity of superoxide dismutase (SOD) in the T1 and T2 treatments, with elevated levels of this enzyme. The same occurred for the glutathione S-transferase (GST) enzyme in liver tissue, and malondialdehyde (MDA) in gill tissue. Differences in the villi (p<0.05) were observed in the intestinal tissue. Fish submitted to the feed with 0% PFR presented measures significantly larger in villi height, width, and apex, in the middle intestine, compared to treatments with 12% inclusion of PFR. This indicates that lettuce produced additional effect in the filtration of nutrients such as ammonia. The inclusion of passion fruit residue in the diet did not compromise the zootechnical performance of the experimental animals, having great potential for inclusion in diets for juvenile tilapia.