Pica can occur in all types of cattle and is mainly an outdoor problem.
Cattle in certain paddocks may eat clay or tree-bark in those paddocks but not in adjoining paddocks. Grass in those areas may be grazed to the ground. Some outbreaks have no known cause and may not be solved by laboratory tests on blood or feed. The problem is more aesthetic than economic, as general herd health and productivity is usually normal. The causes are largely unknown .