Major trace elements limiting livestock performance in New Zealand.

Abstract Extract • Many New Zealand soils are naturally deficient in cobalt and/or selenium and/or copper, or are naturally high in molybdenum. livestock granng pasture grown on such soils may be deficient in one or more of these trace elements. • In the 1940s and 1950s, New Zealand researchers were at the forefront of research to define the cause of trace-element related ill-thrift and clinical diseases like white muscle disease, peat scours and enzootic ataxia. • New Zealanders have devised production-related reference ranges for blood and liver copper, vitamin B(12) and selenium that are used for the diagnosis and prevention of deficiencies. • A range of supplementation procedures has been devised, from topdressing or spraying pasture to direct animal supplementation, to suit the range of livestock management systems found in New Zealand. • Trace-element monitoring programmes are now a routine procedure for farmers grazing cattle, sheep, and deer on trace-element deficient land. • Copper deficiency is the main trace-element deficiency diagnosed in deer.