Yellow discoloration in veal calves: the role of hepatic copper.

Liver samples from four groups of calves were analysed chemically and histologically for copper and iron levels. Milk replacer-fed 'yellow' calves were compared with milk replacer-fed 'white' calves, concentrate and silage-fed 'pink' calves and concentrate and silage-fed young 'red' fattening bulls. In the milk replacer-fed calves high copper and low iron levels were measured in the liver, whereas in the concentrate and silage fed pink calves and fattening bulls lower copper and higher iron levels were found. The yellow calves appeared to be icteric and had chronic hepatitis. Their hepatic histopathology was characterised by fibrosis, cirrhosis, fatty change, increased amounts of stainable copper, necrobiosis and prominent cholestasis; some animals had intranuclear inclusion bodies in the hepatocytes. They had similar or lower hepatic copper levels than the white calves and varying iron levels, indicating that copper toxicity was not the primary cause of the hepatic damage.