How Can Tetany Be Avoided?
Mature, lactating beef cows are most at risk for grass tetany. If turn out can be delayed until grass is at least six inches tall, the risk for grass tetany is greatly reduced. New grass growth in cool spring weather tends to have lower Mg levels, but incorporating legumes in the pasture will increase the Mg content of the forage in the spring diet.
Since cows cannot readily mobilize body stores of Mg to maintain healthy blood levels, they need daily Mg supplements, especially those feeding on lush growing grass. Dry lot or finishing rations should also be evaluated.
Cattle at lower risk for grass tetany (stocker calves or dry cows) should be placed on high-risk pastures. In the short term, prevention of grass tetany can be accomplished by supplementing Mg in the diet.
Feeding high magnesium minerals before placing cattle under conditions favorable for grass tetany can greatly reduce the chances of tetany occurring. Feeding between 1 0 and 12 grams per head daily of highly-available magnesium the month before tetany is likely to occur can help prevent the problem from happening.
Resource: Iowa State University