Understanding Nitrates and Methods to Manage

By Corissa Wilcox, MSc, AAg, Livestock and Feed Extension Specialist, Swift Current

August 2024

Are you considering feeding cereal greenfeed or crops that have been stressed due to drought or frost? It is valuable to test your feed sources this upcoming fall to ensure nitrate levels are safe. Plants require nitrogen for photosynthesis and growth. However, when plants are exposed to environmental stressors, their ability to break down nitrate may be affected. When fed to ruminant livestock, nitrates (NO₃) are broken down into nitrites (NO₂) and can be toxic if levels are in excess, which could lead to nitrate poisoning.

Many common crops grown in Saskatchewan are susceptible to nitrate accumulation, depending on growing conditions. Cereal crops grown for feed such as barley, oats, triticale and rye are at a higher risk of accumulating nitrates. Other less common crops such as corn, millet, sorghum and canola can also accumulate nitrates. Here is a more comprehensive list of crops that may accumulate nitrates.

Feed Testing

The ideal time to test for nitrates is after the feed is harvested. For feeds that have been baled, a forage probe can be used to collect a sample. If sampling prior to harvest, take a representative sample from various locations in the field. Forages left for grazing re-growth can be sampled by taking clippings at the height which the livestock will graze the plant to. Collect the feed sample in a large plastic bag and remove the excess air prior to sending for lab analysis.

Management

If nitrate levels exceed 0.5 per cent of the total diet (dry matter basis), it is recommended that management is adjusted help mitigate the effects of high nitrate feeds. Management adjustments may include:

• Blending high nitrate feeds with other feeds to decrease the nitrate concentration in the diet to a safe level. This may require livestock to be adapted gradually to the diet to adjust to higher nitrate levels.
• Ensuring that nitrate levels in water are safe, as it can cause an additive effect when nitrates are high in the diet.
• Considering the time of feeding and class of cattle: Avoid feeding to sick and gestating/lactating animals as nitrates can limit oxygen supply to the fetus.
• Increasing the number of feedings to two to three meals per day versus one meal.
• Adding grain to the ration to enhance nitrate degradation (2 to 5 lb. per head, per day) while still providing a balanced diet.
• Avoiding using non-protein nitrogen (urea) as a protein supplement.
• Providing a mineral supplement to help degrade nitrate.

Testing your feed and water for nitrates is the only way to know your risk and protect your livestock. Contact the Agriculture Knowledge Centre at 1-866-457-2377 to connect with your regional livestock and feed extension specialist for assistance with feed testing, interpretation, nitrate adaptation and ration planning needs.