This NebGuide describes symptoms, causes, prevention and treatment of nitrate poisoning in livestock. Managing High Nitrate Feed Nitrate in Water Treatment Sampling and Testing Feeds for Nitrates Nitrate poisoning in cattle occurred long before the use of nitrogen fertilizers. In the late 1800s there were reports of cornstalk poisoning in Nebraska, and nitrate poisoning from oat hay in North and South Dakota and from weeds in the high-organic matter soils in Florida and Wisconsin. Nitrate concentrations in feeds for livestock depends more on plant species and environmental conditions prior to harvest than on the amount of available nitrogen in the soil. Nitrate is not always toxic to animals.
Most forages contain some nitrates.
When feeds containing nitrates are consumed by ruminants, nitrates are changed in the rumen to ammonia that is, in turn, converted by bacteria in the rumen into microbial protein. Nitrite is one of the intermediate products in the breakdown of nitrate and is the cause of nitrate poisoning. Some nitrite is absorbed into the bloodstream. Nitrite in the bloodstream changes hemoglobin to methemoglobin. Hemoglobin carries oxygen from the lungs to other tissues but methemoglobin is incapable of carrying oxygen.