Copper is mainly involved in photosynthesis in the chloroplasts. A consequence of deficiency is the paling (chlorosis) of the young leaves. Copper is also involved in the formation of cell walls, especially of lignin. Deficiency also results in a lack of rigidity. Finally, copper also plays a key role in protein synthesis. Particularly in cereals, deficiency is visible due to discoloration of the tips of the leaves (white tip disease) and as empty ears at harvest (dysfunction in pollination). Excess copper hinders root development by inhibiting the microbial activity of the rhizosphere. It may also lead to ferric chlorosis. In livestock, deficiency leads to growth disorders, infertility, pica syndrome, anaemia, hair discoloration and a susceptibility to infection.