By Chrissie Lawrence
ALTHOUGH STAGGERS has so far been rare this spring, that could quickly change following recent warm weather and heavy dews.
Wet, lush grass with low dry matter content could trigger hypomagnesaemia, warns independent vet consultant Tony Andrews. “Timing of fertiliser application and whether nitrogen or potassium has been applied will also have an effect,” he adds.
“It is likely fertiliser applied this year has not thoroughly been absorbed, preventing uptake of magnesium.” When applying fertiliser, Dr Andrews advises applying well before stock go onto grass and avoiding application of potassium during the fast lush growth season.
But the Potash Development Association (PDA) reckons it is wrong to assume the application of potash automatically leads to mineral disorders. “Far too much grassland is short of potassium because of fears over staggers,” says PDA”s Chris Dawson. He believes staggers is not caused directly by fertiliser use.
Magnesium percentage in plants is affected by a large number of factors, according to PDA”s latest leaflet, Potash, Magnesium and Sodium Fertilisers for Grass. Increasing uptake of one nutrient by the plant may affect the level of others, but it is wrong to assume applying potash automatically leads to mineral disorders, it claims.
On farms where staggers is a recurring problem, attention should be given to the potassium, magnesium and sodium content of herbage. Where mineral disorders are a problem, PDA recommends taking herbage samples when grass is growing actively, such as May, to check on potassium, magnesium and sodium status. It also suggests taking soil samples every four or five years to check on fertility status and trends.
But because staggers is mainly associated with lush spring growth, when magnesium and sodium percentage are low, it is best to apply potash dressings after the spring flush, from June onwards, advises the PDA. Small more frequent applications can also be beneficial and once in balance potash requirements of grazed grass are small because most potassium is recycled back to the sward in dung and urine.
But for producers currently turning cattle out in areas prone to staggers, Dr Andrews says there are a number of preventative measures which can be taken. “Feeding concentrate before turnout, controlled grazing and offering magnesium while stock are grazing can help.”
However, he advises avoiding using magnesium supplements in water as cows may not be willing to drink, particularly when lush grass is on offer.
Gordon Hemmingway of Glasgow University Vet School adds that dusting pastures with magnesium oxide or use of magnesium hydroxide-containing sprays can ensure the whole herd is supplemented.