August 23, 2001

Dairy Specialist Offers Advice on Feeding Scabby Wheat

With wheat scab a problem in the region again this year, some livestock producers may want to use the grain as a low cost feed.

"Fortunately, the feed value of scabby wheat is often good," notes J.W. Schroeder, North Dakota State University Extension Service dairy specialist. "The grains may contain mycotoxins that can limit livestock performance, so some caution is necessary."

Wheat scab (also known as head blight) is caused by a fungus called Fusarium graminearum. Scab severity is very erratic in the region, depending on weather conditions during heading. The disease can reduce both yield and quality of the grain. The disease organisms can also produce the mycotoxins DON (vomitoxin) and zearalenone (an estrogen analog). Neither of these toxins is considered carcinogenic or highly toxic.

Because the mycotoxins are concentrated in the grain, baled wheat straw from affected fields should be safe for most uses, Schroeder notes. However, it probably should not be used for breeding livestock.

Swine are most susceptible to the toxins. As little as 1 part per million of DON can significantly reduced daily weight gain in pigs, especially those weighing less than 150 pounds. Higher concentrations result in feed refusal and vomiting. Non-breeding cattle and poultry seem to tolerate both toxins better than swine. Research at NDSU indicate sheep and beef can tolerate fairly high levels of DON. University of Manitoba researchers fed barley contaminated with DON at levels of 24 parts per million to mid-lactation Holstein cows. The diets had no significant effect on feed intake, milk yield, rumen pH, or milk composition.

Schroeder says there is some variability in sampling methods and tests for DON, so producers should allow a margin of error in interpreting and applying test results.

If scabby wheat is used as feed, it should be tested for both DON and zearalenone content. Testing is available from the North Dakota Veterinary Diagnostic Laboratory at NDSU in Fargo. For more information, contact the laboratory at (701) 231-8307. Testing requires at least one-half pound of a representative sample. Grain, silage, and straw can be tested. Specialists recommend taking many small samples and combining them. The test for DON costs $25 for samples from North Dakota citizens and $30 for out-of-state samples. If tests for zearalenone or other mycotoxins are required, the test is $50 for in-state samples.

"Because research on dairy cattle has been limited, there is no specific data on the effect of vomitoxin on reproduction," Schroeder notes. "As a result, some specialists recommend that vomitoxin-infected grain should not be fed during breeding and the first trimester of pregnancy."

"Producers need to keep in mind that the toxicity of the feed containing vomitoxin may be increased when other mycotoxins such as aflatoxin, zearalenone and other fusarium molds are present," he says. "Also remember that sick animals or those with compromised immune systems are much more susceptible than healthy animals."

Schroeder says producers who have scabby grain should have it tested for vomitoxin. "If tests are positive, mix the contaminated feed with undamaged feed to dilute the toxins to bring it within the recommended guidelines. If you must use moldy feed, be sure it is tested, and if the vomitoxin levels are much above the suggested guidelines, it may not pay to feed them at all. Highly contaminated feeds may impair growth rate, weight gain, animal health, and milk production, mostly due to decreased feed consumption and toxicity problems which interfere with the metabolic processes in the animal, resulting in economic loss to the producer."

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Source: J.W. Schroeder, (701) 231-7663, jschroed@ndsuext.nodak.edu
Editor: Tom Jirik, (701) 231-9629, tjirik@ndsuext.nodak.edu

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