Drought puts cows in Midwest at risk of nitrate poisoning

Jul 26, 2012

Junior Roberts’ cows near Billmore, Missouri, are lucky. The grass they’re grazing on just tested negative for high levels of nitrate. But Roberts says he’s not through testing his 1,400 acres, and he knows that many farmers are selling off their herds rather than pay for alternative foods for their cattle.

“You’d be better off to sell them then to turn them in on a field where they’re gonna lay down and die,” he says. “It’s a problem if that’s all they’ve got left to eat and it’s poison. It ain’t gonna do them no good. You’re gonna lose them plum completely.”

His fields that are close to the Eleven Point River here in south central Missouri are doing okay…but the ones up on higher ground produced less than half the normal yield of hay this year.

He removes the chain from the gate leading into a parched, brown field.

“This up here usually makes four and a half to five round bales an acre, round bales. This time, it made like a bale and a half. It was real thin up in here. It’s just baked,” he said.

So, a science refresher: all plants bring up nitrate from the soil. But they need moisture—rain—to convert that into protein. The drought means many plants, especially tall grasses and weeds, are toxic right now. Cows suffering from nitrate poisoning appear to be suffocating, because their bodies can’t transport oxygen. It often causes female cows to abort.

Roberts took samples of his forage to the University of Missouri extension office in Oregon County.

“We’ve probably had at least one a day, sometimes more.”

Sarah Kenyon is an agronomist with the extension service. She’s the one who tests the forage for nitrate poisoning when farmers bring in their samples.

She pulls a bottle of solution out of a box.

“We take the forage and we split the stem,” she says, “and we put the drops on the stem. If the solution turns blue, it contains nitrates. If it does not turn blue, then it is safe,” she says.

She says many samples are showing nitrates, putting cattle farmers in a tight spot: they can do further testing to see how high their nitrate levels are. If they can afford it, they can buy alternative feed…or they can head to the sale barn early, which many here have opted to do.