Find out forage content before supplementing

It’s all very well buying in mineral supplements to re-address deficiencies on farm. But how are producers to know which need to be supplemented and what is being wasted?

Making informed decisions on cost-efficient nutrient supplementation is not always easy. Numerous factors including the weather disrupting silage and haymaking, can have considerable effects on nutritional value and quality of forage produced.

Crops cut late are more mature than is ideal, resulting in high fibre and low protein contents. Other crops that are lifted in wet conditions will have low dry matter and low sugar contents.

These adverse factors can lead to poorly fermented silages of low nutrient value, with knock-on effects on amount and type of supplement required to maintain animal performance targets. Concentration of trace minerals in forages are the most highly variable of any nutrients required by animals.

Therefore, animals on forage– based diets are most at risk of trace element deficiency. To establish if amount and type of supplement being fed to balance the forage is appropriate, it is essential that forage quality is known.

Trace mineral concentrations are affected by four interdependent factors: Species or variety of crop; type and mineral concentration of the soil; climatic or seasonal conditions; and fertiliser programme (sulphur and potash).

Troubleshooting mineral deficiency

The first step in identifying trace mineral deficiencies is to rule out other more directly contributing factors that can be the cause of decreased animal performance such as worm burden, disease incidence and diet.

Secondly, be sure that proper management of free choice trace mineral feeding is offered. Are animals being offered a continuous supply of fresh mineral? Are they consuming the mineral at the recommended level?

Know the trace mineral contribution of available feedstuffs. Collect forage samples, being careful to select forage animals are actually grazing or consuming. Perform a standard trace-mineral evaluation of forage.

Ideally, drinking water should also be analysed, given that antagonists in the water such as iron or sulphate may affect availability of copper.

Assess the herd trace mineral status. In some instances it may be important to confirm or disprove a potential trace mineral deficiency by examining trace mineral status through blood and/or liver collection.

Liver samples provide the most reliable indicator of actual animal stores of copper and selenium, but are more difficult to obtain.

Preventing trace mineral deficiencies

Sub-clinical trace mineral deficiencies occur more frequently than recognised by most livestock producers, because there may not be visible symptoms that are characteristic of a trace mineral deficiency.

With a sub-clinical deficiency, animals grow or reproduce at a reduced rate, using feed less efficiently and operate with a depressed immune system.

Therefore, forage should ideally be tested for trace-elements and any trace element supplementation of the diet formulated accordingly to prevent potential trace element deficiencies in animals.

When and how to take forage samples

Ideally, silage pits should be sampled before winter feeding by taking core samples throughout the pit so winter rations can be planned in advance.

Autumn is the optimum time to take samples, before full rations are being fed. The analysis of a representative sample taken from several points across the silage face will assist the investigation of current problems.

A composite grass sample taken from several areas in the field is adequate, which ideally should be taken late spring.

What does a forage analysis tell you?

A forage analysis report will reveal deficiencies for essential trace elements in the forage, but also whether excesses of antagonistic trace-elements could potentially be reducing the availability of trace elements.

Many trace-element interactions have been proven. These include zinc-iron, copper-iron, copper-sulphur, copper-molybdenum and copper-molybdenum-sulphur interactions.

It has been shown that an excess of sulphur, molybdenum and iron in the diet can interfere with the usage of copper and may result in deficiency symptoms even though levels of copper in the diet are adequate.

In the UK, limited trace elements most common in forages are copper, cobalt, selenium, iodine and zinc.

What is a balanced/tailored mineral supplement?

A tailored and balanced mineral is specifically formulated to match the deficiencies/antagonism found in the results of the forage analysis.To balance antagonism of trace-elements in forage and increase availability it should, ideally, contain chelated trace-elements.

Are tailored mineral supplements more expensive?

A quality mineral has its price, particularly when chelated/organic trace-elements are being used.

However, a properly balanced tailored mineral will always be more cost-effective than a standard mineral, since it only supplies required compounds to balance deficiencies and reduced availability of specific trace elements in the forage.

Whereas a standard mineral could provide an excess of some trace-elements and not enough of others, a tailored mineral will also reduce environmental concerns about excessive excretion of minerals and trace-elements into the environment.