Effect of diet supplementation with trivalent chromium on Piaractus mesopotamicus (Holmberg, 1887) at different stocking densities. Physiological parameters

Abstract

The objective of the work was to evaluate the plasmatic cortisol, glycemic and hepatic glycogen levels in juvenile pacu, Piaractus mesopotamicus (Holmberg, 1887), fed diet supplemented and not supplemented with trivalent chromium (0, 6, 12, 18 mg of chromium/kg diet) and maintained at two stocking densities (4 and 20 kg/m³). It can be observed that the fish fed diet without supplementation presented higher plasmatic cortisol concentration than that fed supplemented diet, demonstrating an effect anti-stressing. However, there was not observed any effect (P> 0.01) of the chromium and stocking density on the glycemic values. Fifteen days after the beginning of the experiment, a decrease of the hepatic glycogen in the level of 6 mg chromium/kg and its recovering at the 30th day could be observed. Therefore, in the conditions of the present experiment, the diet supplementation with 18 mg chromium/kg is interesting during the first seven days.