Changes

Trace elements such as '''copper''' are rarely deficient in farm animals, although deficiency can be associated with poor fertility, ill-thrift and leukotrichia - leading to perioccular 'spectacles'.  This reflects the role of copper in the formation of [[Skin - Anatomy & Physiology#Cells of the Epidermis|melanin]].

Trace elements such as '''copper''' are rarely deficient in farm animals, although deficiency can be associated with poor fertility, ill-thrift and leukotrichia - leading to perioccular 'spectacles'.  This reflects the role of copper in the formation of [[Skin - Anatomy & Physiology#Cells of the Epidermis|melanin]].

Excessive exposure to trace elements can also have harmful effects and again, although rare, examples may include '''selenosis''' which is usually seen as [[Skin Glossary - Pathology|alopecia]] in geographical areas with high '''selenium''' soil content for grazing animals.

Excessive exposure to trace elements can also have harmful effects and again, although rare, examples may include [[Skin Nutritional - Pathology|selenosis] which is usually seen as [[Skin Glossary - Pathology|alopecia]] in geographical areas with high '''selenium''' soil content for grazing animals.

===Vitamins===

===Vitamins===