Copper is a vital trace element required by all livestock. Copper deficiency occurs in three main areas in Queensland:
- in sandy soils along the east coast
- in some soils on the Downs extending from Texas to slightly west of Tara
- on the brigalow development area around Taroom and Wandoan.
Other areas are marginally deficient and may have an occasional problem. Plants growing on these soils are copper deficient.
Ruminants grazing in copper deficient country do not receive all the copper they require. Initially, signs are not obvious, as the animals draw on their liver reserves. When liver supplies are exhausted, any of the following signs may become obvious.
Symptoms are rarely dramatic but productivity falls.
Problems usually occur after summer rains produce rapid growth in the pasture. Rapidly growing plants contain low levels of copper. Deficiencies can also develop in animals grazing pastures with adequate copper levels if there are high levels of certain other trace elements, such as molybdenum or sulphur. These can interfere with an animal's copper absorption.
A blood test may provide a diagnosis in an animal from a copper-deficient area. However, an animal may be copper deficient but have normal blood copper levels if it is drawing upon its own body reserves. For this reason, a diagnosis in animals from marginal areas may be difficult to confirm. In these cases, a liver biopsy or liver sample should be done to check liver reserves. Where deficiency is suspected in animals from marginal areas, responses in growth and wool quality to copper supplementation helps confirm a diagnosis.
In the case of sway-back in lambs, specimens of brain and spinal cord should also be examined.
|Treatment and prevention||
A wide range of copper administration methods have been tried with varying degrees of success. These include copper sulphate drenches, salt licks containing copper sulphate, top dressing of pastures and delivery of copper sulphate through the drinking water. It is unwise to treat animals not known to be copper deficient, as too much copper can kill. Obtain a definite diagnosis before starting any supplementation program.
Copper injections are a more reliable supplementation. Injections must be repeated every three months. Injection in mid-pregnancy can prevent sway-back in lambs.
Copper pellets have been developed that are easy to administer with a pellet gun and slowly release copper for several months. This is repeated annually, ideally just before summer.