Select the Right Supplements for Your Cows

By Sherry Hoyer and Erika Lundy-Woolfolk

When it comes to choosing the right mineral package for your cows, one size does NOT fit all. Iowa State University Extension and Outreach beef specialist Erika Lundy-Woolfolk said the decision begins with two factors: the stage of production and the current diet.

“With much of the Iowa cow herd now being turned out on pasture, be sure to compare components formulated for early spring, breeding season or late summer as you consider overall packages,” she said. “Some vitamins, minerals and other additives provide specific value to this diet.”

For example, during the early, rapid growth stage of cool-season pastures and cover crops, it’s important that cows get extra magnesium.

“The vegetative grass is high in potassium, which is antagonistic to magnesium, and without adjusting to fortify the diet, there is a risk of grass tetany,” Lundy-Woolfolk said. “Once grass growth has slowed and the early cool-season species start to head out, the potassium content drops, and the extra magnesium is no longer needed.”