Testing forages is especially important in drought years, when highly variable Conservation Reserve Program (CRP) hay and cornstalk bales are being utilized. But tell your lab to use wet chemical analysis rather than near-infrared spectroscopy (NIRS), suggest Joe Sellers and Steve Barnhart, Iowa State University Extension beef specialist and agronomist, respectively.
“The forage types present in CRP are quite diverse,” Sellers says. Most labs offer both forage analysis options. However, NIRS uses calibrations established with traditional forages and may not satisfactorily analyze a non-traditional mix.
Check for nutrient content as well as higher nitrate concentrations in baled cornstalks or summer-annual forages such as sorghums or millets harvested and stored as dry bales, Barnhart says.
Before testing corn silage, wait until ensiling is complete – about 30 days, he adds. “Corn silage is generally tested for protein, energy and other nutrient values, but producers also should add a nitrate test to the order, to determine if excessive nitrate levels have persisted through the ensiling process. Producers should take a good, representative sample from the pile, trench or bag silage storage shortly after feeding is started.”
Local farm suppliers or ISU Extension laboratories can help. Iowa producers looking for forage sampling recommendations and test-report interpretation, and help in developing rations can contact local ISU Extension and Outreach beef program specialists.