Dry pastures, low-quality roughage and the variable mineral content of corn silage are leading to many undernourished cows in Iowa, said Beth Doran, beef specialist with Iowa State University Extension and Outreach.

“I’m more concerned about the excessively thin cows than the overly fat ones,” Doran said recently at a beef cow management meeting in Holstein. “I don’t see a lot of overweight cows out there in the country right now.”

A particular concern is a cow’s access to protein during pregnancy,...