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Mineral supplementation is big business in livestock farming, with considerable sums of money invested on an annual basis.
We need to ask ourselves, however, if our enterprises benefit from their use and are minerals really the source of problems with which we associate them.
This was a question posed by Dr Nigel Kendall of the University of Nottingham at last week’s Teagasc lowland sheep conferences in Offaly and Donegal.
Nigel said minerals are frequently raised as the underlying cause for a range of on-farm problems, from poor lamb performance to poor conformation, higher barren rates, dirty tail ends and anything in between.
Part of this reliance on minerals stems from the fact they are widely and easily accessible and often deliver a feel-good factor that animals have been treated and therefore should perform better.
It is not minerals!
Nigel stresses that while there are farms with identified mineral problems, for many, minerals are not the root of the problem with which we associate them. He said dry matter intake should be the first and most important consideration, with minerals further down the investigation list.
We need to look at the overall diet and ask is there enough energy and protein to sustain the desired performance
“Grass supply and what I like to refer to as Vitamin G should be first and foremost.
"We need to ask is there an adequate supply of grass or forage and what is the quality like?
"We need to look at the overall diet and ask is there enough energy and protein to sustain the desired performance.”
Nigel said another element that is not given the importance it deserves is water supply.
An inadequate supply of water will limit performance no matter how good the diet offered is and will lower dry matter intake.
Longer term, there can be associated health issues. When these factors have been assessed, the next area to investigate is health status with parasitism, overall flock health and mineral status highlighted as three key areas which have the ability to greatly influence performance.
Identifying problems
As forage is the main component of intake in sheep production systems, Nigel says it is a good place to start investigations.
If testing samples, it is important to differentiate and take samples from areas where vegetation or land type differs significantly.
If testing conserved forage, this can be carried out at harvest, with the mineral status staying the same from once the crop is harvested.
This will allow feeding programmes to be tweaked as desired well in advance.
A lot of farmers invest in labour and money to supplement ewes with cobalt when it most likely is a waste of money
Account also needs to be taken of seasonality, with cobalt raised as an example.
The level of cobalt in grazed grass dips in the period from April to October when it is marginally below the cobalt requirement for ewes (0.1 mg/kg DM) but can be significantly below the requirement of grazing lambs (0.2 mg/kg DM).
“I am not even sure the requirement for ewes is 0.1 mg/kg DM. A lot of farmers invest in labour and money to supplement ewes with cobalt when it most likely is a waste of money.”
Trials at Athenry have shown this to be the case with no effect of cobalt supplementation to ewes pre-joining.
Anything else the animal is consuming should also be analysed where problems exist including concentrates or forage crops and also water.
Unlike ingredient inclusion levels feed merchants are obliged by law to state the mineral status of the feed on the bag or provide it on the docket in the case of bulk feeds.
Water may also be of concern where it is coming from a non-mains source such as a bore hole.
Soil concentrations are not necessarily reflected in grazing as plant uptake is affected by other factors including pH, water content and even compaction
Animal blood tests are a good indicator of mineral status, while liver tests will give a good indication of long-term mineral status and identify low or high accumulations.
Urine tests can be used to investigate macro mineral status or iodine supply.
Nigel favours forage analysis over soil analysis as sheep eat the forage and therefore forage analysis gives a more accurate estimate of mineral status.
Soil concentrations are not necessarily reflected in grazing as plant uptake is affected by other factors including pH, water content and even compaction.
The previous history of the farm should also be taken into account as it can be a valuable insight.
The use of on farm trials or sentinel groups can also be successfully implemented to aid or confirm decision making, with this especially beneficial in providing information.
Treatment considerations
A treatment programme should be developed on the back of an accurate diagnosis. It should take into account the high-risk periods and how long supplementation will be required for.
It should also take into account any animal-specific concerns such as some lowland breeds being more susceptible to copper toxicity, for example.
Note should also be taken of significant future management changes such as a change of environment from grazing to housing as this can cause copper toxicity or sudden changes in the diet offered .
Where there is a marked difference in land type or forage on the farm then the supplementation programme will need to take this into account.
Nigel highlighted a farm he has been working with to explain this point.
Low-cobalt fields were used to conserve silage to be fed out as part of a TMR diet while lambs grazed there had access to creep feed to take account of the low-cobalt status.
On more elevated lands there was no issue with cobalt status and ewes and lambs could be grazed without supplementation, while on a more marginal part of the farm sheep required direct cobalt supplementation.
It is important to weigh up how serious the mineral imbalance is and ask if there will be a return achieved and if the cost of supplementation will be covered by the gain achieved
Nigel advised farmers to be wary of what is on offer when selecting minerals as there is a huge disparity in quality.
“Not all minerals do what they claim. Ask the mineral company to show you evidence they work.
"Ask them to show you the trials that demonstrate there will be a value from you investing in their product.”
Nigel also highlighted another point that needs to be taken into account: “Remember, it is also an option to do nothing too. It is important to weigh up how serious the mineral imbalance is and ask if there will be a return achieved and if the cost of supplementation will be covered by the gain achieved”.
If the deficit is not very significant then the gain achieved may not be worthwhile while Nigel explains that over supplementation and mineral toxicity is now also becoming a growing problem in livestock enterprises.
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