What’s Grass Tetany?

By Marty New

Grass tetany, also known as grass staggers, wheat pasture poisoning, and hypomagnesia, is a magnesium deficiency of ruminants usually associated with grazing cool-season grasses during spring.

It is most prevalent among older cows in early lactation, but it may also affect young or dry cows and growing calves. The reason is thought to be older cows are less able to mobilize magnesium reserves from the bones than younger cows. Grass tetany occurs most frequently when cattle are grazing lush, immature grass and tends to be more prevalent during periods of cloudy weather.

Symptoms include incoordination, salivation, excitability, and in the final stages, tetany, convulsions, and death. Since the progression of the disease is relatively rapid, often the only sign of a problem is a dead animal.

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