Livestock farmers are recommended to put more emphasis on effective magnesium supplementation around turnout this spring, particularly for lactating cows and ewes.

According to Rumenco technical manager David Thornton, rising pasture potash levels are depressing magnesium availability in the rumen.

However, David points out that the negative effects of high potassium levels can be offset by increasing sodium intake.

Extra sodium in the diet helps improve magnesium absorption from the rumen, where a grass mineral analysis can be helpful in order to determine the risk posed by high potash levels.

David said: "Analysis of average potassium levels in spring grass reveals an upward trend, probably due to increased slurry and muck applications rather than any extra usage of potash fertilisers, but the danger of magnesium ‘lock up’ and threat of grass staggers is very real this year.

“For example, the dairy cow requirement for potassium is only 1 - 1.4 per cent of dry matter intake, so the levels in grazing alone far exceed this need even before any other dietary ingredients are included.

“For the first six weeks post turnout it’s crucial that your magnesium supplement includes extra sodium.

"It is for this reason that Supalyx Magnesium contains 6 per cent sodium (equivalent to 15.5 per cent salt), as well as 15 per cent highly available magnesium.

“Suckler cows with calves at foot or calving at grass are particularly at risk this spring because in most situations they do not receive any additional feed. Many cows may also be coming out of the winter period in poor body condition, simply because economics dictate they go through winter on a high forage only system.

"The combination of last year’s high quality end of year grazing and a housed winter on average quality conserved forage in many cases means that cows are ill-prepared nutritionally for the key grass staggers risk period.”

How important do you think magnesium supplementation is? Let us know on our Facebook page, don't forget to give us a like!

For more information on Rumenco livestock feeds please visit