As drought intensifies, many farmers are deciding to harvest drought-stressed crops for livestock forage. In some areas of the state, farmers have already harvested small grains as hay.

While these crops can be a valuable resource for livestock producers short of forage, North Dakota State University Extension specialists warn that there is an increased risk of nitrate poisoning with many drought-stressed forages.

“Plant stresses such as drought can increase nitrate levels in plants,” says Miranda Meehan, NDSU Extension livestock environmental stewardship specialist.

Nitrate accumulation is influenced by various factors, such as moisture and soil conditions and plant type.

“Nitrate poisoning may occur if livestock eat drought-stressed crops and forages, which can accumulate nitrates,” says James Rogers, NDSU Extension forage crops production specialist. “Feeding drought-stressed forages from oats, barley and corn causes the majority of North Dakota’s nitrate poisoning cases.”

However, a number of other plants also can accumulate nitrate, including wheat, sudangrass, sorghum-sudan hybrids, turnips and pearl millet. If producers are considering utilizing low-yielding crops as livestock forage, they should be tested for nitrates before feeding.

Not all drought conditions cause high nitrate levels in plants. Some moisture must be present in the soil for the plant to absorb and accumulate nitrate. In plants that survive drought conditions, nitrate levels are often high for several days following the first rain. Severe drought-stressed areas — such as hilltops with very sandy soils — might have plants that look bad, but these plants may be so stressed that they are not accumulating much nitrate at all unless there is a recent rain event.

“Plants have to be in active growth stages to take up nitrogen from the soil,” says Meehan. “Nitrate hot spots in fields have had moisture, so although they are stunted in growth, they typically look very lush and green.”

Stress from the period from plant jointing to heading is associated with more nitrate accumulation. Fields that have nitrogen fertilizer applied are also more susceptible to accumulating nitrates.

Nitrate toxicity is not typically an issue on rangelands. However, pastures with nitrate-accumulating broadleaf plants such as kochia, pigweed and Russian thistle can be a problem because these plants usually are green, so livestock will consume them, says Meehan.  

Plant parts closest to the ground contain the highest concentrations of nitrates. Leaves contain less than stalks or stems, while the seed and flower usually contain little or no nitrate.

“The risk of poisoning can be reduced during haying by raising the cutter bar above 6 inches or by monitoring grazing livestock and removing them when the plant stubble height is at 6 inches,” says Rogers.

Ruminant animals, such as cattle and sheep, are susceptible to nitrate poisoning because their digestive process converts nitrate to nitrite, which in turn is converted to ammonia. When nitrate levels are high, the nitrite accumulates and is absorbed by red blood cells, reducing their ability to transport oxygen.

The same reaction takes place in horses’ hindgut. However, it occurs to a much lesser extent; thus, nitrate poisoning is very rare in horses.

Clinical signs of nitrate poisoning are related to the lack of oxygen in the blood. Acute poisoning usually occurs from a half hour to four hours after livestock consume toxic levels of nitrate. The onset of symptoms is rapid:

• Bluish/chocolate brown mucous membranes
• Rapid, difficult or noisy breathing
• Rapid pulse (150-plus beats per minute)
• Salivation, bloating, tremors, staggering
• Dark chocolate-colored blood
• Weakness, coma, death

“If nitrate toxicity is suspected, avoid moving or stressing cattle, as their blood oxygen levels may be dangerously low,” says Dr. Jake Galbreath, NDSU Extension veterinarian. “Unfortunately, in most cases, dead animals will be the first sign, so it is important to contact your veterinarian to rule out other potential causes of sudden death.”

Pregnant females that survive nitrate poisoning may abort because of a lack of oxygen to the fetus. Abortions generally occur approximately 10 to 14 days following exposure.

Laboratories can analyze suspected plants, but samples need to be representative of the field or bales in question. Samples should be packaged in a clean plastic bag and shipped to a laboratory. Contact an NDSU Extension agent for more information on nitrate testing.

The best way to prevent nitrate poisoning is to control the type and quantity of forage offered to livestock, says Dr. Galbreath. He recommends the following:

• Avoid forages with potentially toxic levels of nitrate, or at least diluting them with feeds low in nitrate.
• When grazing, feed dry roughage first to reduce the number of affected plants that hungry animals ingest.
• When feeding baled forages, be sure to take representative sample cores from bales that represent the entire field.

“Also, be sure you don’t overstock pastures when grazing high-nitrate forages,” says Rogers. Overstocking increases the amount of high-nitrate plant parts (stems and stalks) that are consumed by livestock.

Nitrate content of small grain forages can also be reduced by up to 50% by chopping and ensiling. Make sure the silage has time to ferment (21 days), and test it before feeding. Dilute with other feeds accordingly.

For more information on utilizing drought-stressed crops for feed and nitrate poisoning, check out the NDSU Extension publications “Managing Stressed or Damaged Crops for Livestock Feed” and “Nitrate Poisoning of Livestock.”

NDSU Agriculture Communication – Aug. 6, 2026

Source: Miranda Meehan, 701-219-9251, miranda.meehan@ndsu.edu

Source: James Rogers, 701-857-7682, james.rogers.1@ndsu.edu

Source: Jake Galbreath, 701-231-5738, j.galbreath@ndsu.edu

Editor: Dominic Erickson, 701-231-5546, dominic.erickson@ndsu.edu