Not a lot is known about the requirements of goats for trace elements like iodine, selenium, copper and cobalt. The diet of goats on lifestyle blocks is restricted to what we offer them, and their diet is more likely to be deficient in some elements than a diet of natural browse. In that case, are lifestyle block goats at risk of deficiency diseases?
We know that as a general rule goats don't seem to require as much of some essential trace elements as sheep or cattle. However they do seem to have a higher requirement for iodine, and goat kids, particularly Angoras, may need relatively more selenium.
- In iodine deficient inland areas, goitre can occur in newborn kids whose mothers have not been given supplementary iodine while pregnant.
- Goitre is a swelling of the thyroid glands at the top of the neck just below the throat.
- Affected kids are born weak and susceptible to cold weather.
- Iodine deficiency can be induced in goats or in their foetuses by feeding brassicas (such as kale, swedes, choumolier, cabbage etc) and clovers. These contain chemicals (goitrogens) that reduce thyroid hormones.
- In older kids iodine deficiency takes another form - myxoedema. This is an odd condition in which the kids' growth is stunted, their skin is thickened and they look "podgy".
- To prevent the disease, does can be given an oral dose of potassium iodide at intervals of 3 to 6 months or they can be given a subcutaneous long-acting iodine injection.
- In lower-risk areas, providing iodised salt licks may be sufficient.
- About a third of NZ's soils are deficient in selenium. Most cattle and sheep farmers are aware of this and give their stock supplements and goat farmers should do the same.
- If does are deficient in selenium and/or vitamin E, they may be infertile or their kids may be born dead or with heart muscle damage that can cause weakness or sudden death.
- As they get older, kids with selenium deficiency don't grow well and they may be stiff and reluctant to move because of skeletal muscle damage. This is white muscle disease.
- If the soil on your farm is deficient, selenium can be added to fertiliser and top-dressed onto pasture.
- It can also be added to anthelmintic drenches or long-acting selenium injections can be given.
- It's very easy to overdose, and even giving two or three times the recommended dose can be fatal, so discuss what's required with a knowledgeable vet.
- Selenium deficiency can be diagnosed by your vet taking blood samples from your goats and having them tested for selenium,
- Copper deficiency isn't common but in a few areas soils are deficient in copper, and deficiency diseases can occur in cattle and sometimes in goats and sheep too.
- In goats it shows up as 'enzootic ataxia', a disease characterized by hind limb weakness at 1 to 4 months of age leading to hind leg paralysis
- Copper deficiency may be diagnosed by your vet, who can arrange for tests to be carried out on blood or liver samples.
- Cobalt deficiency is unlikely to be a cause of unthriftiness in young goats, because as a general rule goats are less susceptible to cobalt deficiency than other classes of stock.
- It has been shown that even on a cobalt deficient farm where cobalt supplementation boosted lamb growth rates, it had no effect on the growth rate of young goats on the farm.
- However a few cases of 'white liver disease' thought to be associated with cobalt deficiency have been reported from various parts of the country in young angora cross goats.
- The signs were very poor growth rates, facial eczema type sunburn and on post mortem, pale swollen livers.
- Unusually rapid spring pasture growth may result in high levels of soluble carbohydrate in pasture, and it has been suggested that this could precipitate the deficiency state.
The bottom line
While some trace element deficiencies can occur in goats, they are not common. However goats in selenium-deficient areas should receive some selenium supplementation and it's best to consult a vet to avoid overdosing. Goats in iodine-deficient areas should receive long-acting iodine injections, although in marginally deficient areas iodised salt licks may be sufficient.