How to work out your flock’s trace element requirements

Trace elements are minerals such as copper, selenium, cobalt, iodine, manganese and zinc that are essential for life. Optimal flock performance depends on them being supplied correctly.

But how do you start figuring out your flock’s mineral status? Dr Fiona Lovatt explains how to negotiate the minefield of working out flock trace-element status while avoiding getting fleeced by buying unnecessary products.

Sheep obtain trace elements from many sources including forage, supplementary feed, water, the soil, and any supplementation or treatments which may have been administered.

See also: How ewe liver tissue tests are helping to fine tune rations

With certain minerals, such as copper, other factors need to be considered including the levels of iron, sulphur and molybdenum, which can hinder the uptake of copper by the animal.

Why do a mineral audit?

To understand the trace-element situation on your farm, you should undertake a whole farm audit, which aims to cover all sources of minerals and sets that against the changing needs of your livestock through the year.

Different categories of sheep (ewes, lambs, tups) have different requirements which vary through the year. This must be compared with what is already available from the land.

Reaching for a multipurpose supplement without first understanding the detail of the requirements of your flock and the in-built supply that is already on your farm is, at best, a waste of money.

More worrying, there may not be any need to a supplement at all. This scattergun or “just in case” approach carries the risk of oversupply – which can lead to fatal mineral toxicity.

I have seen cases where thousands of pounds were being spent on “bespoke” mineral solutions that were not only unnecessary but also an extreme toxicity risk to the sheep.

What the audit requires

Peeling back the layers of every source of vitamins and minerals – including not only the land and the forage grown on it (or bought in), but also water sources and supplementary feeds/additives – is crucial to fully understand where you are starting from and the best trace-element policy in your flock.

Systematically mapping out your farm and identifying all mineral resources is helpful to address any deficits and avoid oversupply.

Using limited data or guesswork to make the decision on mineral supplementation can result in costly mistakes.

On one farm, had we not taken this thorough approach, we could have missed a major issue – an extremely high concentration of iron in the spring water supply.

The expensive free-access mineral buckets used on the farm also contained high levels of iron, but not the mineral the sheep actually needed, so they were removed, eliminating a substantial cost.

How to rectify mineral supply

Sometimes it just takes a small tweak to allow a sufficient supply of minerals from the existing on-farm sources. However, in other cases, targeted supplementation may be required.

Frequently, what may have been put down to a trace-element deficiency is found to be inadequate dry matter intake or insufficient energy or protein supply. This can be remedied by providing access to better quality grazing rather than buying minerals.

Free-access mineral supplements come at a significant cost and can be difficult to manage. Some sheep will not eat any, others will overconsume. This type of supplement can contain high levels of unnecessary elements, and I do not recommend it as an effective solution.

Treating clinical deficiency

Drenches and injectables have their place in treating clinical deficiency, although it is important to realise there is not necessarily a direct correlation between quality and price.

As a rough estimate, it is never reasonable to expect to get more than a week’s supply of cobalt out of any drench. In contrast, selenium levels will usually remain high for about six weeks.

Where it has been identified that a longer-term supply is necessary, the higher-quality oral boluses (such as Cosecure where copper is needed, Zincosel or Agrimin) can offer a targeted and specific approach to managing trace-element nutrition over a longer period.

Where the on-farm trace-element supply is insufficient, ewes require a constant, controlled supply from eight weeks before tupping. Some trace elements, such as cobalt, cannot be stored by the sheep so these must be supplied on a daily or weekly basis where needed.

For many people, mineral nutrition has become an expensive minefield, but we are unravelling the mystery by careful auditing and then advising appropriate evidence-based actions.

How to conduct a mineral audit

Generally, the need for mineral audits is highlighted when working with your vet or flock health adviser during your regular flock health planning sessions.

During these sessions it is highly valuable to reassess all dietary regimes to get the best return on your investment.

Alternatively, an exploration of the mineral status of the farm and livestock may be suggested during disease, poor breeding or growth performance investigations.

• Audits should start by mapping out the farm to identify mineral supply and flock requirements which will depend on the time of year.
• Forage and/or grass samples should be analysed. Some companies will offer subsidised forage testing. Ensure the test includes an analysis of mineral content and is independently interpreted. Where water is not coming from a mains supply, collecting water samples for analysis is usually recommended.
• At this point, bloods samples can be taken from sheep to obtain further information. If this is necessary, ensure sufficient time has elapsed since supplements were last administered so levels aren’t artificially high. Liver samples from deadstock, cull ewes or slaughter lambs can also be helpful, particularly when there is a concern of copper overload.
• Work with your vet/adviser to understand what samples need taking, how many, and which laboratories to use.
• Interpret the results with your vet/adviser alongside any historical test results you may have. Interpreting this data can be complicated and is best undertaken with a vet who is confident with the concept of mineral auditing.