by Richard F. Randle, DVM,UNL Extension Beef Cattle Veterinarian Grass tetany, sometimes called grass staggers or hypomagnesaemia, is a metabolic disorder of cattle, related to a deficiency of magnesium (Mg). Early lactation cows are the most susceptible, with older cows considered more susceptible than those with their first or second calves. Grass tetany usually occurs in the spring and is typically seen in ...