Topics Included:

• Elevated feed nitrates found across the Northern Plains
• You know what you formulated. Now verify the results with expected values
• More on amino acids by NIR
• Behind the scenes to Dairyland's one of a kind in vitro lab
• Visit us at World Dairy Expo - new crop corn silage summary available

Samples tested through Dairyland Laboratories show a clear increase in feeds containing more than 1,000 ppm nitrate-nitrogen across Nebraska, North Dakota, South Dakota and Minnesota. Through this point in 2026, South Dakota and Nebraska have submitted more samples above 1,000 ppm than in any of the previous five years, while North Dakota and Minnesota have submitted more samples above that level than in any year except 2021. 

Feeds below 1,000 ppm in nitrates are generally considered safe for cattle, sheep,  

and goats. Results above that level do not necessarily mean a feed cannot be used, but they indicate that its inclusion rate, the complete diet and nitrate exposure from drinking water should be evaluated.

Drought conditions are likely to blame

Plants absorb nitrate from the soil as part of normal growth. Under favorable conditions, they convert nitrate into amino acids and proteins. When plant growth is interrupted by drought, nitrate uptake and conversion can become unbalanced, allowing nitrate to accumulate in plant tissue.

The 2026 growing season produced that risk pattern, with late-summer drought affecting much of the Dakotas, Nebraska and western Minnesota.

Rain following drought can temporarily increase the risk rather than immediately resolve it. Once soil moisture returns, drought-stressed plants may rapidly absorb nitrate from the soil before they regain the ability to convert it efficiently into protein. Nitrate concentrations can increase for several days following rainfall.

Why nitrates are dangerous for ruminants

Ruminants are particularly susceptible to nitrate poisoning because microbes in the rumen convert nitrate into nitrite. Normally, nitrite is converted into ammonia and used by rumen microbes. When nitrate intake is too high, however, nitrite can accumulate faster than it can be converted.

Excess nitrite enters the bloodstream and inhibits its ability to carry oxygen effectively. Although the animal may still be breathing, its tissues are deprived of oxygen.

Early signs can include rapid or difficult breathing, a rapid and weak heartbeat, anxiety, muscle tremors, weakness and staggering. As oxygen deprivation becomes more severe, the animal’s gums and other mucous membranes may appear blue or brown, followed by collapse, seizures and death. The blood of a severely affected animal may have a characteristic chocolate-brown color.

The danger depends on the nitrate concentration, how much affected feed is consumed, the rate at which it is consumed, the remainder of the diet, nitrate in drinking water and the animal’s condition. 

The following University of Wisconsin feeding guidelines are expressed as nitrate-nitrogen, or NO₃-N, on a 100% dry-matter basis:

• Below 1,000 ppm NO₃-N: Generally considered safe.
• 1,000–2,000 ppm NO₃-N: Generally safe when fed in a balanced ration. For pregnant animals, limit the affected feed to no more than half of total ration dry matter and make sure drinking water is low in nitrate.
• 2,000–4,000 ppm NO₃-N: Limit the affected feed to less than half of total ration dry matter. Make sure the complete ration is adequately fortified with energy, minerals and vitamin A.
• Above 4,000 ppm NO₃-N: Potentially toxic and should not be fed.

Nitrate exposure is cumulative. A forage that can be used safely at a limited inclusion rate may become dangerous when combined with nitrate from other feeds or drinking water. Results should therefore be interpreted as part of the complete diet rather than evaluating each ingredient in isolation.

Actions to take if you suspect high nitrates

With most of this year’s forage already harvested, the priority is identifying affected feeds and managing them appropriately before feeding.

Use extra caution with pasture and any remaining harvest. Rain does not immediately eliminate the nitrate risk in drought-stressed plants. Nitrate concentrations can temporarily increase after rainfall as plants rapidly resume nitrate uptake. Avoid harvesting drought-stressed forage for several days following rain. Pasture requires particular caution because nitrate levels can vary widely and animals selectively consume plants and plant parts, making representative sampling difficult.

Test ensiled feeds before feeding. Proper ensiling typically reduces nitrate concentrations by 40–60%, making it a useful tool for lowering risk in moderately affected forage. It is not a cure-all: forage containing very high nitrate concentrations at harvest may remain unsafe after fermentation. Test the finished silage rather than estimating its nitrate concentration from a pre-ensiling result.

Consider nitrate from drinking water. Nitrate risk is cumulative across the entire diet. A feed that can be used safely at a limited inclusion rate may create a problem when combined with nitrate from other feeds or the water supply. When elevated nitrate is found in feed, consider testing the water and evaluating total nitrate exposure with a nutritionist.

For additional sampling information, visit our our nitrate resource page resource page. Feeding guidelines are adapted from University of Wisconsin Extension guidance on University of Wisconsin Extension guidance on nitrate poisoning in livestock

Knowing whether a feed result is acceptable shouldn't require manually reviewing every result against formulation targets. Our new Expected Values feature allows you to enter the target values used to formulate or accept a feed and automatically applies the allowable variations established by AAFCO to help determine whether the results fall within an acceptable range. Each result is then assigned a status based on where it falls relative to your expected values and the applicable AAFCO variation:

• No flags. All results are within the target values.
• Out-of-Expected-Range. At least one result is outside the expected range, but all values are within the allowable variation established by AAFCO.
• Out-of-Spec. At least one result falls outside the ranges for AAFCO allowable variation and was confirmed through additional testing. 

These statuses are shown with your results (Figure 1) and included in email and mobile app notifications to help you quickly identify potential issues.

Use cases:

• Verify mixes against formulation targets
• Set acceptance criteria for minimum or maximum nutrient values
• Create consistent QA standards across products and batches

Setting up Expected Values is easy. Enter your targets when submitting an eSample through the Dairyland Labs Portal, mobile app, or simply send the feed tag with your sample. If you use Lot Management, your Expected Values can be saved to the feed and automatically applied to future samples from that lot.

The Expected Values feature is available with any package at no additional cost for all nutrients with an established AAFCO allowable variation.

Moisture · CP · Lysine · Crude fiber · Fat (EE or AH) · Ash

Salt · Ca · P · Mg · K · Na · Zn · Mn · Cu · Fe · Al · B

Figure 1. The Expected Values report provides an overview of the value measured in the lab, expected values from the feed tag, and AAFCO allowable variation. Results that may require additional attention are flagged. 

Over the next few months, you’ll notice additional amino acids appearing in NIR reports for the NASEM Complete and CNCPS 6.5+ packages. Arginine, threonine, tryptophan, and cystine are important variables in swine and poultry diets. While they generally aren’t considered limiting in dairy diets, they have interesting behaviors in silages and other attributes that could make them useful measurements for dairy in the future.  

Ensiling’s impact on amino acids

The process of ensiling alfalfa and corn silage results in a significant reduction in some amino acids (arginine, tryptophan, and cystine) while others are mostly unaffected (phenylalanine, alanine, isoleucine). Attributes of these individual amino acids may explain why:

Arginine – When microbes metabolize arginine, the pathway produces ATP directly, giving the microbes more energy than they could get from other options. Arginine also continues being degraded at lower pH levels than other amino acids because it is preferred by acid-tolerant organisms like lactic acid bacteria.

Cystine – The oxygen-free environment inside a silo makes it easy to break the sulfur bond that holds cystine’s primary components together. Once that bond is broken, its components are attractive targets for microorganisms.

Isoleucine, leucine, and valine – These branched-chain amino acids are less impacted by ensiling because microbes must go through a more complicated process to degrade them. Interestingly, lactic acid bacteria have a limited ability to create enough of these amino acids for their own needs, so they absorb and incorporate them into microbial protein, effectively preserving them to be used by the cow instead of degrading them.

Could these amino acids become important in dairy diets?

Maybe, but the evidence is mostly around transition cow supplementation and the link to silages is weak.

Arginine – A recent study showed that supplementing rumen-protected arginine to transition cows resulted in over 5 lbs. of additional colostrum produced per cow. It’s unlikely that arginine concentration in silage has much impact on dairy performance because most arginine in forages is degraded in the rumen anyway. Still, it’s a precursor for nitric oxide which regulates blood flow, potentially making it important for transition cows due to its impact on mammary blood flow, placental blood flow, and nutrient transfer to the fetus. 

Tryptophan – Through its function as a precursor to serotonin, tryptophan participates in calcium mobilization around calving and mammary calcium transport. Some studies have shown an impact of supplementing other serotonin precursors to transition cows, but not tryptophan itself.

Cystine – Like arginine, cystine is very reactive in the rumen, making it unlikely that its concentration in silage has much impact on the amount a cow absorbs directly. Cows do have the ability to convert methionine to cysteine (the primary component of cystine), so it’s plausible that increasing cystine concentration could spare methionine for milk protein production.

Threonine – In pigs and poultry, threonine requirements increase during intestinal disease or stress. The same principles could matter in dairy cows, but direct evidence is limited.

For now, these additional amino acids should be viewed as useful information rather than new dairy formulation targets. We do not have evidence that the lower concentrations of arginine, tryptophan, or cystine observed in silages limit milk production or rumen function. However, measuring them consistently will help us better understand how fermentation changes feed protein and evaluate whether they become useful in future dairy models.

Ever wonder what happens behind the walls at Dairyland? Thanks to Midwest Farm Reports your questions are now being answered in this, the first of three videos showing the work that happens in the lab each day!

This first video takes you behind the scenes to Dairyland's one-of-a-kind in vitro lab where all of the digestion assays and many research projects are completed.

Investing in the future of testing, Dairyland manages a small herd of animals to provide the freshest rumen fluid so your results are truly cow tested!

We hope you enjoy and reach out to our team with any questions!

Visit us at World Dairy Expo

We look forward to seeing you Sept 26 - Oct 2, 2025 at World Dairy Expo in Madison, WI.

You will find us in two locations on the Expo grounds:

• in Exhibition Hall, at Booth #EH 4104, and
• staffing the Forage Superbowl Booth at the south end of the Trade Center.

We will have a variety of staff attending over the duration of Dairy Expo. Be sure to talk with us about the new crop corn silage summary, or any other items of interest. We look forward to visiting with you!

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Dairyland Laboratories, Inc. | 608-323-2123 | Email