Supply with the trace elements zinc, copper and selenium in horses in the south of Bavaria

In a field study samples of 106 horses from 13 farms were investigated. Feed-, blood-, cover hair- and hoofhorn-samples were taken and the zinc, copper and selenium content was determined. In the blood samples the glutathionperoxidase activity (GSH-Px activity) was also determined. The rations of the horses were calculated. 57% of the horses did not meet their zinc requirement and 75% did not reach their selenium requirement. In contrast the copper intake in most horses (85%) was sufficient. No horse fed with locally grown feed covered the zinc or selenium requirements. Many horses that received an uncontrolled supplementation of concentrates and mineral feed did not reach the recommended zinc and selenium supply. In many cases the plasma levels of zinc (in 30%) and selenium (in 71%) were lower than the reference values. In the investigated range of zinc, copper and selenium supply the plasma levels, as well as the content in cover hair and hoofhorn, showed no strict correlation with the zinc, copper or selenium intake. The GSH-Px activity was also not clearly correlated with selenium intake or selenium plasma levels.