Vomitoxin Levels and Testing in Wheat
Posted: July 1, 2014
Much of the wheat in the state is still a week away from harvest but it will be coming off soon. Now that the wheat has yellowed it is more difficult to see the bleached spikelets which are the head scab infections. Hopefully you scouted and identified any problem fields with greater than 25% of the heads affected by scab. It is a good idea to segregate grain from those fields infected, from the clean fields at harvest.
There are a number of commercially available mycotoxin quick tests that can be used, including GIPSA Performance Verified Mycotoxin Test Kits. Select a test kit that tests for DON in ppm and is approved for wheat.
Pennsylvania has a good fact sheet on Mycotoxin Management. This document lists the FDA guidance levels for DON in animal feed and food. Infested grains testing 10 ppm or less for DON may be used in animal feed according to the advisory based on the species, portion of the diet and level of DON. FDA does not recommend the use of grain with levels of DON that exceed 10 ppm in animal feed.
To achieve a more accurate estimate of the degree of mycotoxin contamination, it is critical that the collected grain sample actually represent the entire bin or truckload of grain. Follow these tips on how to collect a random sample:
- Obtain a minimum of 12 samples from different locations in the bin or truck, and bulk all into one. The total weight of the composite sample should be approximately 10 lbs.
- Hand mix the sample. Subdivide the 10 pound sample into two 5 pound subsamples. The sample size required varies from one laboratory to another. Studies have shown that the chances of detecting parts per million (ppm) or parts per billion (ppb) levels of toxins in samples are greatly reduced with a smaller sample size. Choose one 5 pound sample to be sent to the laboratory for analysis.
- Make sure that the moisture content of the sample does not exceed 13 percent. Samples high in moisture cannot be processed immediately. This results in delays and may allow mycotoxin levels to increase during shipment.
- Pack the sample in a paper bag (not plastic) and place it in a container with a note stating the type of services you wish the laboratory to perform.
- In a few special cases there are some advantages of collecting a biased sample. For instance, if there is evidence of moisture damage due to a leak in the bin, it may be more appropriate to collect a sample from the moistened spot and another from the dry area.
Both growers and grain buyers should consider testing their grain. A quick test informs the grower of a potential issue with grain quality and the grain buyer will benefit from knowing the quality of the grain they have purchased.