University of Wyoming Extension News

High-nitrogen spring forage could pose cattle health problems

Early moisture has resulted in abundant grass in many Wyoming pastures.

This early lush grass is high in nitrogen and may be low in certain minerals such as magnesium; both can lead to cattle health problems, said a University of Wyoming livestock nutrition expert.

Jim Waggoner, an associate professor in the College of Agriculture’s Department of Renewable Resources, said loss of old forage in many of the state’s range areas due to periods of drought the last several years has added to the potential problem. The old grass typically dilutes high nitrogen in the early grasses and decreases its potential negative effects on cattle grazing the area. It also helps reduce incidences of grass tetany, which is associated with an imbalance of minerals such as magnesium, calcium and phosphorus in early spring growth forage.

In addition, this old growth grass helps reduce the incidence of larkspur poisoning that is prevalent in many areas in the state, Waggoner said.

One approach to help reduce these potential problems is to delay cattle turn out until there is at least 3 to 4 inches of grazable forage in the pasture.

“The natural reaction people are having is they want to turn their cattle out now on to this great-looking early forage, and I can certainly understand that,” said Waggoner, a range/livestock nutrition specialist with the UW Cooperative Extension Service (UW CES).

In addition to health problems, high nitrogen levels can, for example, suppress food intake.

“That compounds the problem as cattle will stop grazing before their nutrient needs are met resulting in weight losses and decreased milk production,” he said. “You can bring animals back in off the pastures and offer them hay, and they won’t eat it. Put them in a corral, and lock the gate. In two or three days, their blood has cleaned up, and they’ll start eating hay again.”

Waggoner advised waiting an extra 10 days to two weeks before turning cattle out on these lush areas and feed a little extra hay and/or a protein and/or mineral supplement to ensure cattle are in shape to make optimum use of the lush grass resource.

“The urge to get the cows off of dry feed and out on grass into pastures is high,” he said. “But hang on for that extra 10 days or so and get more hay or protein or mineral into them and curtail a potential wreck.”

For more information, contact Waggoner at (307) 766-2365 or, or a local UW CES educator. Contact information is available online at



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