Non-Starch Polysaccharide in Diets for Hybrid Surubim: Effects on Metabolism Plasticity

Abstract

This study aimed to analyze the effect of mango meal, a non-starch polysaccharide, as a carbohydrate source on the metabolism plasticity and performance indicators for hybrid surubim (Pseudoplatystoma fasciatum x P. corruscans), a tropical carnivorous fish. Juveniles (±14.5g initial weight) were fed 3% of total biomass for 60 days in four experimental diets replacing 0, 33, 66 and 100% of the cornmeal. Growth by final weight was evaluated, but statistical differences (p<0.05) were not observed among the treatments. The activity of total alkaline protease was statistically lower in the fish group fed 100% cornmeal substitution. However, trypsin levels also decreased when 100% of the cornmeal was replaced by mango meal, but without statistical significance. Zymograms showed bands of protease and amylase activities for all treatments. Cholesterol (0%-141.83±46.10; 100%-71.36±14.40 mg.dL-1) and total protein (0%-3.98±0.94; 100%-1.70±1.03 mg.dL-1) in the plasma decreased as mango meal levels increased in the feed. On the other hand, glucose (0%-105.08±31.24; 100%-128.11±24.51 mg.dL-1) and free amino acids (0%-24.51±2.62; 100%-38.13±8.94 nmoles.ml-1) in the plasma increased. Although growth was not affected, the carbohydrate source affected fish metabolism, which showed metabolic adaptation by the species. The result suggests that mango meal can replace up to 33% of the cornmeal in diets for Pseudoplatystoma sp.