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Guard against grass tetany this spring

Royce Towns, TFC Nutritionist 2/25/2019


Grass tetany is a potentially deadly condition that can occur at any time of the year but is most often seen in early spring when periods of warmer weather cause rapid growth of cool-season grasses.
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Warmer days and more hours of daylight will be a welcome sight for cattlemen who have battled the cold and mud this winter. Spring pastures will soon follow, bringing with them the potential for grass tetany.

Also referred to as hypomagnesemia or grass staggers, grass tetany is a complex metabolic disorder of cattle associated with a deficiency of magnesium in the blood and spinal fluid. This potentially deadly condition can occur at any time of the year but is most often seen in early spring when periods of warmer weather cause rapid growth of cool-season grasses.

Cattle eagerly consume this new growth, increasing their potential for magnesium

deficiency. Cool soil temperatures impair the plants’ ability to absorb magnesium, resulting in lush, green forage lacking in this vital mineral. Despite more than 80 years of dedicated research, grass tetany still claims a number of cows annually.

One of the most effective means of preventing grass tetany is providing cattle with supplemental magnesium just prior to, and during grazing of high-risk forages. Magnesium oxide is an efficient source of magnesium but is not palatable to cattle; therefore, it’s typically included as an ingredient in “hi-mag” mineral supplements, blocks, or tubs. While these products can be effective in preventing grass tetany, supplementation with a complete vitamin/mineral supplement can offer numerous additional benefits.

Grass tetany season tends to correspond with critical periods in the production cycle of the beef female. Fall-calving cows will usually be in heavy lactation during most of grass tetany season, while spring calving cows will often be in the last weeks of gestation and early lactation. Additionally, grass tetany season immediately precedes breeding season for many spring calving herds. These stages of production, and the physiological stresses they place on the animal, validate the need for enhanced vitamin and mineral nutrition in addition to supplemental magnesium.

It is well established that forages in the Southeast can be deficient in several essential minerals regardless of season. Phosphorus, copper, zinc, and selenium all play vital roles in growth and reproduction of beef cattle. Also, recent research in the field of fetal programming suggests that calves born to mothers that receive adequate trace mineral supplementation will be more productive throughout their lives than those born to un-supplemented females. Since the brain and other vital organs are in critical stages of development during early gestation, nutrient deficits can limit the productivity of the offspring their entire lives. As a result, the benefits of vitamin-mineral supplementation can reach far beyond the cow consuming the mineral supplement.

As you guard against grass tetany this spring, consider the benefits of providing more than just magnesium to cattle. Enhanced reproduction, healthier calves, and faster growth rates await. Visit with the beef cattle specialists at your Co-op to determine which hi-mag mineral supplement is right for your operation.

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