The calendar says it is the beginning of spring and the grass is growing. For most beef producers it is a welcome time of the year because there are no more cold, snowy days to feed hay to the herd. However, there is a hidden danger in those pastures from grass tetany.
This syndrome is a result of low magnesium levels in the circulatory and nervous systems, and it is most common when lactating cows graze lush green pastures. It occurs more frequently when pastures have been fertilized with potassium and nitrogen and when solids are naturally high in potassium and low in sodium. The disease results from low magnesium intake, high potassium and low sodium intakes, and low blood calcium levels (due to heavy lactation).
The symptoms of grass tetany feature erratic behavior in the cow. Restlessness, stumbling, nervousness, isolation, and sometimes a high-stepping movement will occur. The disease will quickly kill cattle with these advanced symptoms without treatment.
Treatment for grass tetany usually requires intravenous injections of magnesium-based compounds from a veterinarian. When a veterinarian is not available immediately and the cow has advanced symptoms of the disease, a precautionary treatment can be applied by saturating a pint of water with Epsom salts and injecting up to 10cc of this solution in multiple locations of the muscle at least four inches apart. Again, this treatment is precautionary and the veterinarian should provide a definitive treatment.
Grass tetany is usually prevented with an appropriate mineral mixture available free-choice to grazing cattle. Commercial mineral mixes that are high in magnesium are readily available. A mix can be made at home, which also features a selenium supplement, with the following recipe (Wahlberg, 1995): 22.5% trace-mineralized salt, 22.5% dicalcium phosphate, 10% 0.06% selenium mix; 22.5% magnesium oxide, and 22.5% ground corn. Cattle should eat about one-fourth pound of the mixture daily.