To prevent grass tetany, spray pasture with a 2% magnesium sulphate solution (epsom salts, 2 pounds to 12-1/2 gallons of water) just before turning animals out.
You might be able to prevent grass tetany on wheat this spring by turning only non-milking animals out to chew it down first.
"So seeding globemallow along with crested wheatgrass may reduce cases of grass tetany
Low concentrations of Ca, carbohydrates, and dry matter, and high concentrations of K, nonprotein N, fatty acids, and organic acids also have been associated with symptoms of grass tetany (Mayland, 1988).
Metabolic disorders including scouring, frequent urination, and reduced weight gains have been observed in beef animals grazing Russian wildrye during the spring or early summer, when grass tetany is most prevalent (Rogler and Lorenz, 1970).
Scientists' combined efforts against grass tetany
have paid off in a highly visible way.
Asay and Mayland (1990) found that Russian wildrye had tetany ratio values of 3.2 to 4.6 suggesting that lactating beef cattle grazing it in spring will be at risk of developing grass tetany.
If mineral content is under genetic control and there is sufficient genetic variation, then altering K/(Ca + Mg) values by plant breeding can be an effective, alternative means to reduce grass tetany potential (Sleper, 1979).