DIETARY COPPER REQUIREMENT OF TILAPIA (OREOCHROMIS AUREUS STEINDACHNER)

Abstract

The dietary requirement of tilapia (Oreochromis aureus Steindachner) for copper was investigated by feeding 3 subgroups of tilapia fingerlings with 8 different rurified diets containing incremental levels of copper (0.0, 2.0, 4.0, 8.0, 16.0, 32.0, 64.0 and 128.0 mg copper per kq of dry diet) for 14 weeks. No gross histopatholoqies were noted in any group of fish. Slight reduced growth, but otherwise not acccumpc1nied other signs of deficiency, were indicated in the groups fed the basal diets which contained 0.5 mg Cu/kg. More pronounced reduction of growth, associated with lowered feed conversion were also recognised in fish given 128 .0 mg Cu/Kg. Erythrocyte count and haematocrit levels were also lowered, but similar in other groups. Haemoglobin levels found to be influenced Iron levels in the organs were found to be influenced to some extent by the cooper availability. Zinc levels in various organs showed no particular trends in relation to either iron or copper leels. As no apparent deficiency signs were observed in the fish fed 2.0 mg Cu/kg and beyond, this dietary level was elucidated to be the minimal dietary copper level. The optimal dietary copper level for optimal growth was found to be 8.0 mg Cu/kg of diets.