Causes of variation of copper, iron, manganese, zinc and magnesium levels in bovine livers. 3. The effects of locality.

The effects of locality on the copper, iron, manganese, zinc and magnesium levels in 407 bovine caudate lobe liver samples preserved in formalin for differing storage periods were examined. The mineral determinations, expressed on the wet basis (WB), were made by atomic absorption spectrophotometry after wet ashing of the liver. Two hundred and ten of the liver samples were from cattle from one farm (Farm 1) the remaining 197 cattle being from another farm (Farm 2). The copper, iron and magnesium levels were taken as indicative of the hepatic concentrations at slaughter. Locality had a significant effect (P less than 0,05) on the copper, iron and magnesium levels. All copper levels on Farm 1 fell well below the accepted minimum (33,0 mg/kg). The deficiency appeared to be secondary with the possible implication of sewage effluent. In terms of biological variation the different iron levels appeared of minor importance and no inverse relationship was found between iron and copper. The manganese and zinc levels were interpreted with caution due to the significant differences reported in their hepatic concentrations after six months of storage in formalin. Extremely high zinc levels in individual animals could have been associated with sewage effluent.