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Grass Tetany Prevention

08 April 2013

GLOBAL - Pasture growth will soon begin, and for livestock owners who are short on stored forage as a result of last year's drought, the temptation will be to begin the grazing season as early as possible, writes Rory Lewandowski, Extension Educator, Wayne County.

One of the major risks associated with early spring pastures is the development of grass tetany - sometimes called grass staggers. 

Grass tetany is a metabolic condition of cattle and sheep associated with a magnesium deficiency. Symptoms of grass tetany include animal nervousness, twitching skin, and a staggered gait.

Symptoms are not always observed and the first sign of any problem may be a dead animal. Generally early lactation animals are most susceptible to grass tetany, especially if they are an older animal. Young animals and later lactation animals rarely have problems with grass tetany.

Mr Lewandowski says that grass tetany can be triggered by the consumption of young, succulent cool season grasses including perennials such as orchardgrass, fescue, ryegrass, and bluegrass. Grazing annual cool season cereals like wheat, rye and triticale can also cause grass tetany.

Typically young immature grasses have a high potassium content and a low magnesium content. This, combined with other soil fertility factors increases the risk of grass tetany when grass pastures are grazed early in the spring.

Pastures that are well fertilized with nitrogen and that have high soil potassium levels combined with low soil magnesium levels are at increased risk for grass tetany, warns Mr Lewandowski.

Apparently the grass plant will take up potassium in preference to magnesium in the early spring until soil temperatures warm up.

Another soil fertility factor that can increase the risk of grass tetany is low phosphorus availability, which can be related to low soil pH and low soil calcium level.

Livestock owners that have had problems with grass tetany in the past or have some of the soil risk factors identified in the preceding paragraph should consider the use of a high magnesium mineral fed to livestock beginning prior to pasture turnout and continuing through the spring period.

The mineral mix should include 8 to 12 per cent magnesium. Some livestock owners like to mix the magnesium mineral with some corn, soybean meal or molasses to increase the palatability and insure adequate animal intake.

For more information about grass tetany, contact your veterinarian, or your County Extension office.

TheCattleSite News Desk

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