Copper in pig nutrition : essential trace element, growth promoter, and its potential adverse effects on human nutrition and environment

Abstract

Copper is essential for many physiological functions including iron metabolism, immunity and protection of tissues from oxidative stress. Liver plays a key role in maintaining copper homeostasis and adjustment to fluctuation of copper supply is mainly achieved by liver storage and biliary secretion. The copper requirements of the growing pig are below 10 mg/kg feed. They are normally covered by the feedstuff copper provision and any supplementation is theoretically superfluous. However, because of the growth promoting effect of copper, 150 to 250 ppm supplements are often added in diets of weaned piglet. When this supply of copper is omitted at the end of the post-weaning period, such a dietary copper supply does not influence the copper content of the meat consumed by humans. However, it induces an increase of copper content in pig slurry and, consequently, an accumulation of copper in soils.

The reduction of dietary copper supply close to the requirements is the main way to better control this environmental risk. However, to achieve this goal, the dietary factors that may significantly influence the availability of copper should be accurately known and ranked. Some chelating agents, such as phytates, fibres or fat as well as the level of other minerals such as Zn and Ca may interfere on copper availability. However their actual impact remains to be assessed. In addition, relevant indicators of copper status should be chosen to implement these investigations.