Livestock producers are encouraged to test their green feed for high nitrate levels.

High nitrate levels will cause nitrite poisoning in animals.

"High nitrate levels are an issue this year. We're seeing some high numbers, so producers should be aware that this is a concern," says Glenn Friesen, forage specialist with Manitoba Agriculture. "So they should have a test done at a feed lab."

He explains high nitrate levels tend to occur on fields that have a nitrogen surplus, which was the case this summer for many flooded fields that were seeded late to green feed.

"The plant is busy gathering nitrates during the growing season and converting them as they hit the leaves into protein and other metabolites. When you get a frost, that conversion stops, but the roots continue to take them up," says Friesen. "You end up with the highest concentrations in the lower part of the plant, which is where you want to focus your testing."

"Nitrate feed can be used. It just has to be blended off. How much you blend depends on the concentration, so that's why you need to get that test done," he says.

Friesen says they use 0.4 percent as a benchmark, although the actual level depends on the type of livestock.

"That is the allowable level and beyond that we're concerned with how much blending you would have to do."

He says ensiling a crop in a bunker or in wrapped bales can reduce nitrate concentrations.

"There is no clear science that shows how much it is reduced, but we do know it helps," he says.