25 April 1997

Magnesium levels must be accurate

PRODUCERS should ensure they are feeding the correct level of magnesium to combat grass staggers, particularly during recent colder weather.

Cheshire-based vet Neil Howie warns that cold spells increase risks.

"We are seeing a number of cases of cold cow syndrome too, where cows produce a profuse watery scour. Magnesium absorption in the gut is reduced when dung is loose, causing greater risk of hypomagnesia."

Loose dung can also be caused by over-dosing cattle with magnesium, he cautions. "In some cases, producers are feeding two or three sources of magnesium, and are over-doing it. Check the level in feed and consider whether thats appropriate.

"A cow producing 20 litres should receive about 30g magnesium – thats about 60g calcined magnesite a day. Cows giving over 30 litres a day should receive 90g calcined magnesite a day," says Mr Howie.

"If you choose to administer magnesium via water troughs bear in mind that cows drink 75% of their water intake in the two hours after milking."

Sucklers and dry cows are also at risk, he warns. "Weigh up the best method of ensuring these animals receive adequate magnesium. For sucklers, a magnesium and molasses mix often work well," he adds

And avoid manuring dry cow paddocks, he says. "Manure contains high levels of potassium which reduces magnesium intake and increases staggers risk."