Most farmers are aware of the dangers of magnesium deficiency and yet every year in the UK cow fatalities occur due to grass staggers.
Every single day, the UK’s estimated five million cattle each need to ingest 35 to 40g of magnesium. And if they don’t get enough, problems can be severe with death swift in the worst cases.
For the past 20 years, as herds are turned out on the spring grass, our Mineral Supplements Technical Manager John Lawrence has been battling to spread the magnesium message.
And it’s a simple one. Cow fatalities and lost revenue caused by falling yields, vet bills and disposal costs can be avoided just by making sure sufficient magnesium is supplied, every day.
Mr Lawrence said: “With a cow typically worth £1,000 or more, it amazes me that animals are still suffering and dying for the sake of a few pence a day.”
Cows can’t store magnesium and are completely reliant on a daily dose for milk production – 365 days a year. Grass staggers is simply when the supply of magnesium to the animal is exceeded by the amount excreted in milk.
And the spring turnout – when the grass is growing rapidly and contains the lowest levels of the vital mineral – is considered a seasonal risk period.
Spring grass is often wet, high in protein but low in salt, which is essential for the absorption of magnesium. Lush pastures are also lower in fibre, speeding up digestion and lowering take-up.
The time between spotting the initial symptoms of staggers to death can be as little as six hours with the Agriculture and Horticulture Development Board (AHDB) estimating more than 75% of staggers, or hypomagnesaemia, cases seen in mid-lactation are caused by inadequate dietary supply of magnesium.
Staggers can affect beef and suckler cows, but the AHDB reports subclinical and chronic disease often goes unrecognized, despite an annual mean incident rate of 3-4% in lactating dairy cows.
The symptoms of staggers range from restlessness, teeth grinding and twitching to staggering, aggressing behaviour and paralysis. Magnesium is also essential for nervous system function, bone growth and fibre digestion.
Mr Lawrence said: “A range of clinical signs can be present, but the most common symptom is acute disease or sudden death. Even subclinical cases can influence performance. Every year, I hear of far too many cases simply because herds are not getting enough of something so readily available.
“Turnout is a high-risk period. However, I have heard of losses in housed heifers on grass silage. Staggers can happen any time there is insufficient magnesium supplementation.
“If you miss any of the symptoms and the herd becomes stressed in any way, like with worsening weather, the condition accelerates, giving little to no time to save the cow. “Magnesium may not be palatable, so it makes sense for every cow to be able to access it in as many ways as possible, in rations, mineral blocks and drinking water.”
Mr Lawrence admitted it was a “balancing act” to keep staggers at bay, and magnesium prices were rising, but added: “It is still far cheaper to make sure enough magnesium is available than it is to lose a cow.”
Increased supplementation is crucial all year round but particularly in the first four to six weeks after turnout – and it’s a good idea to begin a week ahead to give the herd a boost.
It’s harder to measure intake from free access products like blocks and licks when they’re out in the field, helping – or not helping – themselves.
Mr Lawrence concluded: “The only way to make sure is to provide several sources. In the daily ration, to guarantee each cow gets the correct level, or if that is not possible from free access to high magnesium products, and in water troughs, and remember to ensure free access to salt in palatable licks and blocks.
“With all the magnesium products available today the message could not be clearer. If you don’t give her enough…she could die.”