By Karen Stewart, ruminant nutritionist, SAC Consulting

I have been facilitating a Rural Innovation Support Service (RISS) group of farmers who found that when they were looking to purchase minerals for their suckler herds, there was a variance in the advice given, making it a confusing market. They wanted to be armed with more knowledge to make informed decisions about purchasing minerals for their stock.

RISS groups are farmer-led projects on topics that groups have felt there is a need to investigate an idea or issue further.

We analysed the groups’ silages and focussed on what minerals they were feeding in the run-up to calving. It was amazing the range of different specifications of minerals used for farms that are all very similar in their systems.

One of the 12 units was purchasing a mineral specifically made to complement the forage they were feeding. It is more commonplace to purchase a mineral from a range rather than have minerals custom-made and the point of the exercise was to answer the question “how do we decide which one to purchase?”

Many mineral purchases are made on the marketing/sales and what is perceived to be required on a particular farm rather than looking at what requirements are based on the feeds being fed.

From the meetings we have had so far, the farmers in the group have been given information from their forage analysis and looking at cow requirements to see how well their minerals are meeting requirements.

Antagonists that affect absorption of some minerals were taken into account and a level of safety margin on allowances provided. This is important as when feeding cows, a group of animals is being fed, not individuals and therefore intakes will vary.

There was varying results in the group between farms in terms of what was being supplied from the forage and supplements, with none of the farms having the perfect match, some were further out than others.

The biggest variance found in the purchasing of minerals designed for suckler cows in late pregnancy were:

Calcium ranged from 0-20%

Phosphorus ranged from 0-12%

Magnesium 5-20%

Vitamin E ranged from 1500-5000iu/kgDM

Trace elements variation was huge as was the source of trace element used. There was also a big difference in the cost between farms which in itself focusses the mind!

Which minerals are right?

It comes down to meeting the requirements of the animal and taking into account the forage being fed. Doing a forage mineral analysis every three years will give a good indication what is coming from the base ration and where specific issues may lie. Either under feeding or over feeding certain elements can affect output and care needs to be taken when using some specialist products.

For example, a zero calcium mineral pre-calving is a specialist product stemming from the dairy industry to encourage cows in very late pregnancy to increase the absorption of calcium in the body in preparation for milking. Dairy cows go from zero milk to high quantities so quickly this is an aid in prevention of metabolic issues at calving time.

Suckler cows do not have the same demand as dairy cows in this area and also have a much longer pre-calving dry period. It is often multi-factorial with magnesium and other elements involved here too. So the danger here is that a zero calcium mineral is fed for too long (longer pre-calving period than in dairy) and then sometimes don’t transition the cow on to a suitable mineral straight away after calving.

Decisions about what mineral to feed need to be based on facts about what is coming from the base ration (for example straw and silage rations vary hugely in mineral content) with the overall aim to meet requirements and not feed elements in excess.

From this RISS project, the farmers in the group are developing a greater understanding of what is required when choosing mineral supplements and some have made changes to their nutritional management as a result. To find out more about RISS go to