With the warming and cooling spring weather, W. Mark Hilton, DVM, Dipl. ABVP, Purdue University, is confident he’ll see cases of grass tetany. To prevent this disease, Hilton suggests the following:
• Be sure cows have free choice access to a salt-mineral mix with added magnesium. Most feed companies have a “high-mag” mineral. Make sure it also has about 25% salt in the mix. If you mix your own, a good mix is 25% of each of these: TM salt, Di-cal, Mag oxide, finely ground corn. Mag oxide tastes terrible and you need the corn to force intake.
• If you feed corn gluten or DDGS, you will likely not have concerns with grass tetany as both products are high in Magnesium. About 5# of dry product/ head/day will supply about half the cows Mg requirement each day
• Do not graze small grain (cereal grain) pastures with cows with young calves unless you are force feeding Mg and salt. These pastures are very low in Mg and the highest risk pastures. If you have stocker calves, graze them on this pasture.
• If you fertilized the pasture with potash this spring, do not graze with cows with calves. High potassium in the forage is one of the highest risk factors for grass tetany. Never fertilize grass or mostly grass pastures with potash in the spring. Do it in fall if needed.
• Fertilizing with nitrogen in the spring is a risk factor
• If you have some legume hay, feed some every day to the cows on mostly grass pasture.
• Adding legumes to the pasture mix is a great way to decrease the chance of having grass tetany, but it is not foolproof. Grass grows faster than legumes in the early spring and early mixed pastures are still mostly grass.