Copper is an important trace element in both sheep and cattle for proper development. It is required for bone growth, nervous system development, integrity of the immune system as well as development of the coat and much more. Deficiency can result in diseases such as swayback and osteoporosis, in addition to contributing to poorer growth, reproductive problems, scouring and ill-thrift. Cattle are more susceptible to Copper deficiency than sheep.
In New Zealand Copper deficiency is usually associated with an increased pasture Molybdenum (Mo) concentration, which disrupts the storage of Copper in the liver. Even low pasture concentrations of Mo, which are common in NZ, reduce Copper absorption and deplete Copper stores. There is also a seasonal decline, with liver Copper levels being lowest during the winter months.

Because of the reasonably narrow margin between deficiency and toxicity, it is important to get an idea of the Copper status of the animals on farm before treating with Copper. The best times to monitor Copper status are:

• • Cull cows/ewes in autumn and culled growing cattle at any time
  • Ewes in early autumn
  • Pregnant cows in late winter by liver biopsy
  • Rising one year old cattle in mid-winter by liver biopsy

Copper supplementation options include:

• • • Copper boluses which are effective for six to nine months. This will also increase the Copper status in the foetus and lamb from birth to 9 to 10 weeks of age if given in early gestation.
    • Subcutaneous Copper injection which is effective for one to two months.
    • Copper added to drinking water using an in-line dispenser.
    • Top-dressing pasture in autumn or spring. Pasture should not be grazed until after rain, and pasture uptake can be variable.