Mineral supplements – the KISS principle

 Minerals are vital for life. Most minerals have more than one function in the body and contribute to the body's structure, cellular processes, and the immune system.  The vast majority of the 25 minerals required are provided by the diet.  Of the 7 macro minerals (i.e. required in large amounts) required, only 2 are deficient when the majority of the diet is pasture (magnesium and calcium). Sodium can be deficient when more than one third of the diet is a low sodium feed (e.g. cereal grains) and dietary phosphorus can become inadequate in cows grazing fodder beet.  Of the 18 trace elements (i.e. required in very small amounts) essential for life, only 5 are likely to be deficient in pasture-based systems (i.e. cobalt, copper, iodine, selenium, zinc).  Magnesium and the 5 scarce trace elements should be supplemented during the 2-4 weeks before calving and for 4 months after calving. Calcium should be provided to cows in the colostrum herd, but there is unlikely to be a benefit of continued supplementation to milking cows unless the herd is experiencing downer cows.  Concepts like the dietary cation-anion difference (i.e. DCAD) should be ignored unless a mixed ration is being fed to the springer herd.  There is virtually no evidence that " organic " trace elements offer any advantage over strategic supplementation with the cheaper " inorganic " elements.  All sources of trace elements (i.e. pasture, supplementary feeds, water, fertiliser, and mineral supplements) need to be accounted for in dietary plans to avoid the risk of oversupply of any trace element.  Recommendations for supplementation levels are provided. A trace element strategy should be developed in conjunction with your vet.