Test Before Feeding: Oats, Barley, Wheat, and Rye Grown in 2024 May Contain Mycotoxins

September 18, 2024 / small grains

Margaret A Smith, PhD
Forage Agronomist, Albert Lea Seed

Small grains (wheat, oats, barley, and cereal rye) have had a high incidence of diseases this 2024 growing season, including rusts and Fusarium/Scab. These diseases not only reduce yield, test weight, and marketability, but they can also result in mycotoxins that are hazardous to livestock. Several diseases on the grain can result in the formation of mycotoxins. Scab, caused by the fungus Fusarium graminearum and its associated mycotoxins, is often the biggest food and feed quality issue with wheat and barley. This year, oats have also been affected; severely, in some cases.

Definitions:

- Mycotoxins: Toxic substances produced by fungi on the substrate (often grain) where they grow.

- Fusarium graminearum: A fungal organism that causes the disease Fusarium head blight (also known as scab).

- Fusarium/Scab: A disease identified visually by light-tan, light-test-weight seed (“blasted” seed heads), and pink or orangish coloration on seed heads, glumes, and occasionally on the seed, itself. Disease development occurs when high humidity and warm temperatures are prevalent during small grain flowering and early grain development.

- Deoxynivalenol (DON)/Vomitoxin: A mycotoxin produced by Fusarium/Scab. DON production is influenced by environmental factors, including temperature, humidity, available water, pH, and nutrient composition. The fungi that produce DON thrive in cool, wet conditions.

Fusarium produces three important classes of mycotoxins:

1. Trichothecenes (including deoxynivalenol or DON, also known as vomitoxin)

2. Fumonisins

3. Zearalenones

Any of these mycotoxins can affect human health and animal performance and—if enough is ingested—illness or death in hogs, cattle and sheep.

This year, DON (vomitoxin), caused by scab, is widespread on wheat, barley, and cereal rye, but also on oats and, in some cases, at extremely high levels. The worst-affected grain wasgenerally produced in the areas with excessive rainfall (southern MN, northern IA, western WI, and eastern SD).

Animal Responses to DON/Vomitoxin in Feed

Animal responses to DON (vomitoxin) include reduced feed intake or feed refusal, immunotoxicty, vomiting, skin dermatitis, and hemorrhage. Swine are more sensitive to DON than poultry and ruminants, in part because of differences in metabolism of DON. In addition, males are more sensitive than females. 

Levels of DON/Vomitoxin Allowed for Food and Feed Markets

Food: For human consumption, the FDA advises not more than 1 part per million (ppm) DON for wheat, barley, and oat milling and for malting barley. Individual grain buyers may exercise even more stringent requirements.

Feed: Recommendations for animal consumption vary by livestock species and age. In general, 5 ppm is recommended as the maximum in grains and grain by-products. Click here for more detailed information from the FDA, entitled: “Guidance for Industry and FDA: Advisory Levels for Deoxynivalenol (DON) in Finished Wheat Products for Human Consumption and Grains and Grain By-Products used for Animal Feed.”

Fusarium graminearum (scab) can produce other toxins besides DON. Single contamination with DON is not the norm; it is the exception! When DON is present in grain, it is likely to be accompanied by other toxins that can also affect human and animal health. Consider this when testing to determine how best to manage the grain in feed rations.

Grain Testing for Toxins

Grain with high incidence and severity of Fusarium head blight (wheat, oats, barley, triticale, and corn with Gibberella ear rot) should be sampled and tested for DON before being fed to animals or sold to other markets. Feeding without knowledge of your DON/Vomitoxin level can lead to poor animal performance and financial loss.

Mycotoxin Testing Options

Methods for mycotoxin analyses fall into two main categories: 

1. Rapid screening methods

2. Conventional laboratory methods

The better method to use depends on the intended use of the results. For example, is a qualitative (“yes/no”) result enough information, or is exact concentration needed for your buyer?

A rapid screen test may be useful for individual farmers in helping them decide whether or not to truck their grain to a food market. That said, the food grain buyer will conduct more specific lab tests to determine if the grain meets their 1 ppm top limit.

Commercial kits for on-site mycotoxin testing can be purchased from a number of manufacturers.  Click here for USDA information about performance verified mycotoxin tests kits.

Feeding DON/Vomitoxin Infected Grain

For feeding your own grain, you’ll need a laboratory test with the level of DON specified in the results. Laboratories that test for mycotoxins are listed below.

Accurate test levels of DON are needed to manage your plan for feeding. Managing DON-infected grain at any level of infection will likely require a combination of adding mycotoxin binders to the feed and diluting the affected grain in the ration. Check with your animal nutritionist, feed dealer, and veterinarian about the best mycotoxin binders for your specific grain, specific mycotoxin, and livestock species being fed and how best to incorporate the infected grain in your feed ration.

Do not store grain for long periods from fields with high levels of scab. Feed out as soon as possible. The associated DON (vomitoxin) and other mycotoxins levels can continue to increase in stored grain.