[The effect of increased copper supplements in feed on the development of cadmium residues in swine].

In commercial pig fattening copper is added to the feed at a concentration exceeding the requirement by a factor of more than ten. This improves the weight gain of the pigs during the first three months remarkably. In order to study the influence of copper supplementation on cadmium retention, 4 groups of male castrated weanling crossbred pigs (Deutsche Landrasse x Pietrain) received for 3 months a diet containing 1 mg Cd per kg feed, given as CdCl2, as well as 0, 50, 100 or 200 mg Cu per kg feed, given as CuSO4. The liver, kidney, spleen, pancreas, brain, heart, diaphragm, bile and duodenal mucosa were submitted to wet ashing and analyzed by atomic absorption spectroscopy for cadmium. The Cd retention in all tissues increased in correlation to the Cu content of the feed. When 200 mg Cu per kg were added, Cd rose in the muscle from 10 to 15 micrograms per kg, in the liver from 770 to 1720 micrograms per kg and in the kidney, where the highest Cd concentration occurred, from 4620 to 9320 micrograms per kg. This indicates that in pigs the retention of cadmium in kidney and in liver is promoted by Cu supplementation as used in commercial pig fattening.