As spring approaches and grass begins to grow, grazing livestock may experience a forage-related problem known as grass tetany, grass staggers, lactation tetany, or hypomagnesemia. Young cool-season grasses and small grains are commonly associated with this disorder.

Grass tetany is a metabolic disorder caused by reduced magnesium levels in the animal’s blood. In cattle, it generally affects older, lactating cows but can also be seen in dry cows, young cows, and in rare cases, growing calves. Symptoms include nervousness, lack of coordination, muscular spasms, staggering, convulsions, coma, milk yield decrease and death. If you suspect cattle are stricken with grass tetany, a veterinarian should be contacted immediately as early treatment can save animals.

Feeding high magnesium or high “mag” mineral supplements is the preferred method to reduce the occurrence of grass tetany. High “mag” mineral mixes are available at most feed stores and contain higher inclusions of magnesium oxide than other complete mineral mixes. Cattle should begin consuming this high “mag” mineral during the late winter months and into early spring when new plant growth is starting. In late spring once temperatures are consistently above 60 degrees, a producer can quit feeding the high “mag” mixtures.

High mag mineral does not need to be fed year round, but is not problematic if it is. Free-choice high mag mineral should contain 12 to 15 percent magnesium from magnesium oxide. Cattle need to consume four ounces of the mineral supplement daily. Magnesium oxide is unpalatable, which can result in low mineral intake. Co-product feedstuffs such as dried distillers grains, molasses or a flavoring agent is added to the mineral mix to increase palatability.

The season for grass tetany will be developing as temperatures rise and grasses begin to grow. To reduce health problems and livestock death to this disorder, it is important to provide a quality high “mag” mineral or supplement containing Magnesium oxide.

Read more at “Preventing Grass Tetany.”