Selenium is an essential trace element in the diet of many animals. It has a variety of roles within the animal including an important role in growth and fertility. Selenium also acts as a ‘cleaning up’ agent for toxic substances that are produced as animals eat and breathe. Conditions such as White Muscle Disease (WMD), infertility, poor milk production and ill thrift are known to respond to selenium supplementation.
Although the function of selenium is understood by many farmers, vets and agricultural departments across Australia, selenium deficiency still causes significant productivity losses every year.
Selenium deficiency is usually a subclinical condition and producers may not realise that such a deficiency exists.Lambs in particular can suffer severe setbacks from selenium deficiency. In extreme situations losses will occur from White Muscle Disease. As often is the case, once a problem is finally noticed, productivity losses have already occurred.
Adults are also affected by selenium deficiency. Productivity losses will occur as a result of the following:
- Reduced fertility in rams and ewes
- Increased mortality in lambs
- Reduced wool production
- Illthrift and poor growth rates
Selenium in overdose is also potentially poisonous to livestock and for this reason, vaccines containing selenium are marked as Schedule 6 Poisons.Accidental toxicity has resulted from producers giving more than one product containing selenium to their animals at the one time. It is therefore imperative that producers check the label of their products carefully to ensure they do not accidentally overdose their animals with selenium and ensure that the correct dosage of vaccines containing selenium are given.