Research Report: Grass Tetany

Grass tetany is a nutritional disease that occurs in beef and dairy cattle and sometimes in sheep.  It is caused by low amounts of total or available magnesium (Mg) in the diet and is responsible for a large number of deaths in cattle and sheep.  Other names for the disease are hypomagnesemic tetany, lactation tetany, grass staggers, or winter tetany.  Cows are most susceptible when nursing a calf or producing milk.  Also, older cows are more susceptible.

Occurrence:  Grass tetany is common during cool, cloudy, rainy weather and often occurs when cool weather is followed by a warm period.  Tetany generally occurs when animals are grazing cool season grasses or small grain pastures in spring or fall.  Rapidly growing lush grasses are most dangerous.  Plants grown on soils low in available magnesium and high in potassium or fertilized with high rates of nitrogen and potassium are associated with grass tetany.

Recognition:  In mild cases, milk yield is decreased, and animals are nervous.  In severe cases, cows may have a stiff gait, lose their appetite, become nervous and irritable, and have twitching skin.  Later, there may be extreme excitement, convulsions, and labored breathing, or falling on their sides and moving the front legs as if walking.  Death can occur quickly.

Treatment:  Affected cows may be treated by injection of magnesium sulfate solution under the skin or an enema of magnesium chloride solution.  The injections should be given by a veterinarian, since there is a danger of heart failure if they are given too rapidly.

Prevention:  Control grass tetany by (1)  Feeding a supplemental magnesium source; (2) Adding magnesium fertilizer to pasture (early); (3) Dusting pastures with magnesium oxide; (4) Adding magnesium sulfate to water; (5) Moving susceptible animals to legume pastures.

The feeding of Magnesium should start prior to the time that animals are turned out onto new grass.  The program should be continued for at least 30 days into the new grazing season, or until grass “hardens up” enough that danger is past.  Since there is no carry-over of Magnesium in the animal’s system, the recommended amount must be consumed each day.

SILVER MOON HIGH M MINERAL provides a convenient, economical means of feeding the required magnesium.  High M Mineral contains 14% elemental magnesium, with improved dust control characteristics, to assure uniformity.  High M Mineral is quickly soluble in acid solution, and more readily available for absorption in the animal.  A consumption of 2 to 4 ounces of High M Mineral per head per day will provide a daily intake of 8 to 16 grams of magnesium.  Use care in putting out sufficient mineral in convenient locations, so that each animal consumes sufficient mineral each day.  No other salt or mineral products should be offered to animals receiving Silver Moon High M Mineral.  

For more information, or to place orders, talk to your Silver Moon territory manager, or call toll-free to Chillicothe:  1-800-892-2488.