Overfeeding phosphorus isn’t just a problem in lactating-cow rations. Heifer diets also provide excess levels, according to University of Wisconsin research.

Researchers looked at the phosphorus levels in 90 heifer diets in Wisconsin. Of those diets, 86 percent were found to be excessive in phosphorus, says Pat Hoffman, dairy scientist at the University of Wisconsin’s Marshfield Agricultural Research Station.

In fact, phosphorus levels in the diets averaged 0.37 percent of dry matter — the requirement for lactating cows. And, phosphorus levels in some of the diets were as high as 0.62 percent — significantly higher than a heifer’s requirement.

The study also found homegrown forages and feeds can meet phosphorus requirements 54 percent of the time.

“We have a ways to go with cost control and environmental responsibility with dairy replacement heifers (regarding) phosphorus,” Hoffman says.