Share This:

Dr George Fisher - Micro and Essential!

Last updated: 29 Nov 2013


Soil analyses and micro-nutrients - don’t ignore micro-nutrients, they are essential.

Cow and calf


So, how do our livestock break down the energy, proteins and fats in their grass, forage and concentrates, and miraculously bring these building blocks together to produce milk, lay down muscle protein and fibres like wool?  How do they maintain fertile cycles so that they can get pregnant and do it all again next year?

To cut a very long and fascinating story – a whole bunch of molecular transformations happen, primarily in the cells of the liver, muscles, glands and bones, and in blood, (imagine firework sparks flying, compounds whizzing around, electrons flowing like Monday morning commuters at Kings Cross, busily getting to work to do ‘stuff’).  All of this necessary stuff only happens efficiently, (and sometimes only happens at all), because of compounds like vitamins, hormones and enzymes.  They are the fuses that ignite the fireworks and the trains at Kings Cross bringing people together.  At the centre of these are what we term ‘micro-nutrients’ or ‘trace’ elements – Cu (copper), Zn (zinc), Fe (iron) Se (selenium) Co (cobalt), I (iodine), and so on.


We call them ‘micro’ or ‘trace’ because they are needed in much smaller quantities than the nitrogen, phosphorus, potassium, magnesium and calcium of animal feeds, but they are essential.  A lack of any of them, (or an excess of some of them), results in less efficient use of feed by our animals and reduced outputs of milk and meat.

This is really important to our livestock industry – most of the parent rock that has weathered away over millennia to make the minerals and micro-nutrients in the soils of the west of the UK, where most of our livestock are, do not contain sufficient quantities of these life-essential elements.  Consequently, our soils in the west are typically deficient in these essential micros, which means that they are low in many grass and forage systems, which means that animal deficiencies are common.

So, just sample the soil and get some analyses done for micro-nutrients and make amends if the results are low – right?  Well it is not quite as straight forward as that.

Many factors other than soil, including the season, weather and the grasses and forages you grow, will affect the micro-nutrient levels in your home grown feeds.  And you may be feeding other supplements, (concentrates, TMR additives, etc.), that mean that your system is well supplied with micro-nutrients, even if the background levels in your soils are low.

So, what to do?  Get your vet to blood sample around 10% of your stock when they are at their most stressed, (for example, in the last third of pregnancy, or peak lactation, or growing rapidly).  If the results show low levels of relevant hormones, vitamins or micro-nutrients, then take qualified nutritional advice and cover the problem with supplementation immediately.

Feeding cattle_275_231

The next step is to find out where the problem lies in your system – this then means sampling and analysing grass and forage and soils.  Getting to the root of the problem this way will give you a rounded view that will enable you to take the right short, medium and long-term action; that’s perhaps another blog for another day.

The bottom line is, don’t ignore micro-nutrients, they are essential.  Soil analyses might show low micro-nutrient levels; however your animals are fine because of the system that you operate.  You might find ‘adequate’ levels in soils; however your animals are still deficient because of soil sampling errors, or the high output nature of your system.  So don’t rely on the soil alone – it may take you down the wrong path. It is best to take a holistic approach and to sample the soil, grass, silage and bloods at the same time to get the widest possible perspective.


Author: Dr George Fisher