<b>Copper levels in Nile tilapia <em>Oreochromis niloticu</em>s diets</b> - DOI: 10.4025/actascianimsci.v26i4.1713

Abstract

The effects of different levels of dietary copper on growth performance and physiological parameters of Nile tilapia (Oreochromis niloticus L.) were analyzed for 120 days. The experimental design was completely randomized, with five treatments (0.0; 4.0; 80.0; 160.0 and 320.0mg cooper/kg diet as cooper sulfate hepahydrate, 24.05% copper) and six replicates. One hundred and eighty fish, with 2.0 ± 0.05g average initial weight, were kept into 30 aquaria (60L) with individual filter and aeration; water temperature was kept at 25.0 ± 1.0^oC. An albumin-gelatin diet was formulated to contain 32.0% crude protein and 3,200 kcal of digestible energy/kg. The oxygen concentrations and pH were measured weekly. At the end of the experiment, the weight gain, feed conversion ratio and survival rate were determined. Erythrocytes number, hemoglobin concentration, hematocrit ratio, mean corpuscular volume and mean corpuscular hemoglobin concentration were analyzed as hematological parameters. Liver, bones, carcass and muscle copper concentrations were also determined and the liver morphology and coloration were evaluated. Based on the results, it was concluded that either absence or high levels of dietary copper did not determine alterations in Nile tilapia growth performance and hematology; the liver copper concentration is responsive to dietary copper supplementation; high levels of dietary copper determine hepatic alterations and the experimental period is a determinant damage action factor for copper in fish physiological responses.