By Joe Sellers, ISU Extension and Outreach, and Steve Barnhart, Department of Agronomy
It pays to test your livestock's feedstuffs every year, but it is critical to test forages this fall due to extreme variation in quality of silage and hay produced during the drought of 2012. Iowa State University Extension agronomist Steve Barnhart and beef program specialist Joe Sellers said many producers have harvested silage from drought stressed corn, and proper ration development depends on knowing the nutrient content of that feed. Conservation Reserve Program (CRP) forage and cornstalk bales harvested this year also will be variable in quality, making forage analysis essential.
"When testing corn silage, it is best to wait at least 30 days, until ensiling is complete," Barnhart said. "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."
CRP acres were released for emergency haying in Iowa with hay harvested across the state in August.
"The forage types present in CRP are quite diverse, due to seeding mixes used and status of mid contract management," Sellers said. "With this diverse plant mix, producers should request that their forage testing laboratory use 'wet chemical analysis' tests rather than the near infrared spectroscopy (NIRS) test."
Most laboratories offer both options for forage testing, he said. However, NIRS analyses use calibrations established with more traditional forage species mixtures, and may not satisfactorily analyze this more non-traditional mix of forages.
Elevated concentrations of nitrates also may be a concern in baled corn stalks or summer annual forages such as sorghums or millets harvested and stored as dry bales. Testing for nutrient content and nitrates also should be completed for those forages, particularly when harvested following drought conditions, Barnhart said.
Producers can work with their local farm suppliers to arrange forage testing, or can contact laboratories listed in ISU Extension publication 1098A, Forage Testing Laboratories, available for free download. For assistance with forage sampling recommendations and test report interpretation, and to develop rations, contact your local ISU Extension and Outreach beef program specialist.
Joe Sellers is an extension beef program specialist. He can be reached at 641-774-201 or e-mail firstname.lastname@example.org. Steve Barnhart is an extension agronomist. He can be reached at (515) 294‐7835 or e-mail email@example.com.