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Grass tetany can be prevented if steps are taken to avoid problems PDF Print E-mail

By Robert Tigner
SW4 Agricultural
Extension Educator

Fall-planted rye, triticale, and wheat as well as spring pastures soon should be ready to graze. These fields can give great grazing, but be sure you take steps to avoid problems with grass tetany.
Grass tetany is caused by low blood magnesium. Low blood magnesium can be due to low levels of magnesium in lush spring grass, but it also is caused by mineral imbalances like high potassium and nitrogen or low calcium in the diet.
Grass tetany primarily affects older, heavy milking cows or sheep, but young stock also can be affected. It occurs most frequently in spring during cool, cloudy, moist conditions when lush, immature grass starts growing rapidly.
Cattle or sheep affected by tetany often graze away from the herd, are irritable, show muscle twitching, awkwardness and staggering, and they are somewhat wide-eyed and staring.
When affected severely, the animal will collapse, thrash around, throw its head back, maybe lapse into a coma and possibly die.
To prevent grass tetany, first wait to graze until grass is more than six inches tall. Also, feed or graze legumes like clover or alfalfa when you start on pasture since they have high magnesium levels.
Feeding about 10 to 20 grams per day of supplemental magnesium via commercial or home-made salt-mineral mixes may be the best way to reduce tetany problems, but you should start as much as 30 days before grazing begins.
Magnesium oxide is one of the best and cheapest sources of magnesium. Mix equal parts of magnesium oxide with dical, salt and ground corn for a simple home-made supplement that provides adequate magnesium when each cow eats about one pound of the mix per week.
As always, an ounce of prevention is worth a pound of cure.