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Corn Harvest Quality Report 2015/2016

Contents

  1. Harvest Quality Highlights
  2. Introduction
  3. Quality Test Results
  4. Moisture
  5. Chemical Composition
  6. Physical Factors
  7. Mycotoxins
  8. Crop and Weather Conditions
  9. Planting and Early Growth Conditions - Spring (March - May)
  10. Pollination and Grain Fill Conditions - Summer (June - August)
  11. Harvest Conditions (September - October +)
  12. Comparison of the 2015 Average to the 2014, 2013, and 4YA
  13. Corn Production, Usage, and Outlook
  14. U.S. Corn Use and Ending Stocks
  15. Outlook
  16. Survey and Statistical Analysis Methods
  17. Survey Design and Sampling
  18. Statistical Analysis
  19. Testing Analysis Methods
  20. Corn Grading Factors
  21. Moisture
  22. Chemical Composition
  23. Physical Factors
  24. Mycotoxin Testing
  25. U.S. Corn Grades and Conversions
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E. Mycotoxins

Mycotoxins are toxic compounds produced by fungi that occur naturally in grains. When consumed at elevated levels, mycotoxins may cause sickness in humans and animals. While several mycotoxins have been found in corn grain, aflatoxins and deoxynivalenol (DON or vomitoxin) are considered to be two of the important mycotoxins.

As in the previous Harvest Quality Reports, the 2015 harvest samples were tested for aflatoxins and DON for this year’s report. Since the production of mycotoxins is heavily influenced by growing conditions, the objective of the Harvest Quality Report is strictly to report on instances when aflatoxins or DON are detected in the corn crop at harvest. No specific levels of the mycotoxins are reported.

The Harvest Quality Report review of mycotoxins is NOT intended to predict the presence or level at which mycotoxins might appear in U.S. corn exports. Due to the multiple stages of the U.S. grain merchandising channel and the laws and regulations guiding the industry, the levels at which mycotoxins appear in corn exports are less than what might first appear in the corn as it comes out of the field. In addition, this report is not meant to imply that this assessment will capture all the instances of mycotoxins across the 12 states or three Export Catchment Areas (ECAs) surveyed. The Harvest Quality Report’s results should be used only as one indicator of the potential for mycotoxin presence in the corn as the crop comes out of the field. As the Council accumulates several years of the Harvest Quality Report, year-to-year patterns of mycotoxin presence in corn at harvest will be seen. The U.S. Grains Council 2015/2016 Corn Export Cargo Quality Report will report corn quality at export points and will be a more accurate indication of mycotoxin presence in the 2015/2016 U.S. corn export shipments.

1. Assessing the Presence of Aflatoxins and DON

A weighted and systematic testing of at least 25% of the targeted 600 samples across the entire sampled area was conducted to assess the impact of the 2015 growing conditions on total aflatoxins and DON development in the U.S. corn crop. The sampling criteria, described in the “Survey and Statistical Analysis Methods” section, resulted in a targeted number of 185 samples tested for mycotoxins.

A threshold referred to as the Limit of Detection (LOD) was used to determine whether or not a detectable level of the mycotoxin appeared in the sample. The LOD for the analytical kits used for this 2015/2016 report was 2.5 parts per billion (ppb) for aflatoxins and 0.3 parts per million (ppm) for DON. Details on the testing methodology employed in this study for the mycotoxins are in the “Testing Analysis Methods” section.

RESULTS: AFLATOXINS

A total of 185 samples were analyzed for aflatoxins in 2015. This is about the same number of samples (182 and 179) tested for aflatoxins in 2014 and 2013. Results of the 2015 survey are as follows:

  • One hundred eighty-four (184) samples, or 99.5% of the 185 samples, had no detectable levels of aflatoxins (below the 2.5 ppb LOD). This is slightly above the percentages in 2014 and 2013, where 98% of the samples tested had no detectable levels of aflatoxins.
  • One sample (1), or 0.5% of the 185 samples, showed aflatoxin levels greater than or equal to the LOD of 2.5 ppb, but less than 5 ppb.
  • No samples (0), or 0.0% of the 185 samples, showed aflatoxin levels greater than or equal to 5 ppb, but less than 10 ppb.
  • No samples (0), or 0.0%, of the 185 samples, showed aflatoxin levels greater than or equal to 10 ppb, but less than or equal to the FDA action level of 20 ppb.
  • These results denote that 185 samples, or 100% of the 185 sample test results in 2015, were below or equal to the FDA action level of 20 ppb, compared to 100% and 99.4% of the samples tested in 2014 and 2013, respectively.

Comparing the 2015 aflatoxin survey results to the 2014 and 2013 survey results suggests that there were about the same level of incidents of aflatoxins among all ASDs in 2015 as in the 2014 and 2013 crop seasons. While similar, the 2015 crop season had a slightly higher percentage of samples below the LOD than 2014 and 2013. No samples exceeded the FDA action level in 2015 compared to none in 2014 and 1 (<1%) in 2013, which may be due, in part, to more favorable (less stressful) weather conditions in 2015 (see the “Crop and Weather Conditions” section for more information on the 2015 growing conditions). Weather was cool and wet during pollination and grain fill in 2015 and as a result, the corn plants were not under stress. These conditions were not conducive to aflatoxin formation.

RESULTS: DON (DEOXYNIVALENOL OR VOMITOXIN)

A total of 185 samples were analyzed collectively for DON in 2015. This is about the same number of samples (182 and 179) tested for DON in 2014 and 2013. Results of the 2015 survey are shown below:

  • One hundred sixty-one (161) samples, or 87.0% of the 185 samples, tested less than 0.5 ppm.
  • Twenty-four (24) samples, or 13.0% of the 185 samples, tested greater than or equal to 0.5 ppm, but less than or equal to the FDA advisory level of 5 ppm.
  • All 185 samples, or 100%, tested below or equal to the FDA advisory level of 5 ppm.
  • The 2015 percentage for samples that tested below 0.5 ppm (87.0%) is higher than 2014 (80.2%) and lower than 2013 (91.6%).
  • In 2015, 100% percent of the samples tested at or below 5 ppm, which is the same as was observed in 2014 and 2013.

Comparing the 2015 DON survey results to 2014 and 2013 survey results indicates that the percentage of samples with DON results below 0.5 ppm increased in 2015 compared to 2014, but didn’t match the levels recorded for the 2013 crop season. While all survey results were below 5 ppm for all three years, the increase in the percentage of samples that fell below 0.5 ppm in 2015 compared to 2014 may be attributed to weather conditions less conducive to DON development in 2015 compared to 2014.

2. Background: General

The levels at which the fungi produce the mycotoxins are impacted by the fungus type and the environmental conditions under which the corn is produced and stored. Because of these differences, mycotoxin production varies across the U.S. corn-producing areas and across years. In some years, the growing conditions across the cornproducing regions might not produce elevated levels of any mycotoxins. In other years, the environmental conditions in a particular area might be conducive to production of a particular mycotoxin to levels that impact the corn’s use for human and livestock consumption. Humans and livestock are sensitive to mycotoxins at varying levels. As a result, the U.S. Food and Drug Administration (FDA) has issued action levels for aflatoxins and advisory levels for DON by intended use. Action levels specify precise limits of contamination above which the agency is prepared to take regulatory action.

Action levels are a signal to the industry that the FDA believes it has scientific data to support regulatory and/ or court action if a toxin or contaminant is present at levels exceeding the action level, if the agency chooses to do so. If import or domestic feed supplements are analyzed in accordance with valid methods and found to exceed applicable action levels, they are considered adulterated and may be seized and removed from interstate commerce by the FDA.

Advisory levels provide guidance to the industry concerning levels of a substance present in food or feed that are believed by the agency to provide an adequate margin of safety to protect human and animal health. While the FDA reserves the right to take regulatory enforcement action, enforcement is not the fundamental purpose of an advisory level.

A source of additional information is the National Grain and Feed Association (NGFA) guidance document titled “FDA Mycotoxin Regulatory Guidance” found at http://www.ngfa.org/wp-content/uploads/NGFAComplianceGuide-FDARegulatoryGuidanceforMycotoxins8-2011.pdf.

3. Background: Aflatoxins

The most important type of mycotoxin associated with corn grain is aflatoxin. There are several types of aflatoxin produced by different species of Aspergillus, with the most prominent species being A. flavus. Growth of the fungus and aflatoxin contamination of grain can occur in the field prior to harvest or in storage. However, contamination prior to harvest is considered to cause most of the problems associated with aflatoxin. A. flavus grows well in hot, dry environmental conditions or where drought occurs over an extended period of time. It can be a serious problem in the southern United States where hot and dry conditions are more common. The fungus usually attacks only a few kernels on the ear and often penetrates kernels through wounds produced by insects. Under drought conditions, it also grows down silks into individual kernels.

There are four types of aflatoxin naturally found in foods – aflatoxins B1, B2, G1 and G2.These four aflatoxins are commonly referred to as “aflatoxins” or “total aflatoxins.” Aflatoxin B1 is the most commonly found aflatoxin in food and feed and is also the most toxic. Research has shown that B1 is a potent naturally occurring carcinogen in animals, with a strong link to human cancer incidence. Additionally, dairy cattle will metabolize aflatoxin to a different form of aflatoxin called aflatoxin M1, which may accumulate in milk.

Aflatoxins express toxicity in humans and animals primarily by attacking the liver. The toxicity can occur from short-term consumption of very high doses of aflatoxin-contaminated grain or long-term ingestion of low levels of aflatoxins, possibly resulting in death in poultry and ducks, the most sensitive of the animal species. Livestock may experience reduced feed efficiency or reproduction, and both human and animal immune systems may be suppressed as a result of ingesting aflatoxins. The FDA has established action levels for aflatoxin M1 in milk intended for human consumption and aflatoxins in human food, grain and livestock feed (see table below).

The FDA has established additional policies and legal provisions concerning the blending of corn with levels of aflatoxins exceeding these threshold levels. In general, the FDA currently does not permit the blending of corn containing aflatoxin with uncontaminated corn to reduce the aflatoxin content of the resulting mixture to levels acceptable for use as human food or animal feed.

Corn exported from the United States must be tested for aflatoxins according to federal law. Unless the contract exempts this requirement, testing must be conducted by FGIS. Corn above the FDA action level of 20 ppb cannot be exported unless other strict conditions are met. This results in relatively low levels of aflatoxins in exported grain.

4. Background: DON (Deoxynivalenol) or Vomitoxin

DON is another mycotoxin of concern to some importers of corn grain. It is produced by certain species of Fusarium, the most important of which is Fusarium graminearum (Gibberellazeae) which also causes Gibberella ear rot (or red ear rot). Gibberellazeae can develop when cool or moderate and wet weather occurs at flowering. The fungus grows down the silks into the ear, and in addition to producing DON, it produces conspicuous red discoloration of kernels on the ear. The fungus can also continue to grow and rot ears when corn is left standing in the field. Mycotoxin contamination of corn caused by Gibberellazeae is often associated with excessive postponement of harvest and/or storage of high-moisture corn.

DON is mostly a concern with monogastric animals, where it may cause irritation of the mouth and throat. As a result, the animals may eventually refuse to eat the DON-contaminated corn and may have low weight gain, diarrhea, lethargy, and intestinal hemorrhaging. It may cause suppression of the immune system resulting in susceptibility to a number of infectious diseases.

The FDA has issued advisory levels for DON. For products containing corn, the advisory levels are:

  • 5 ppm in grains and grain co-products for swine, not to exceed 20% of their diet;
  • 10 ppm in grains and grain co-products for chickens and cattle, not to exceed 50% of their diet; and
  • 5 ppm in grains and grain co-products for all other animals, not to exceed 40% of their diet.

FGIS is not required to test for DON on corn bound for export markets, but will perform either a qualitative or quantitative test for DON at the buyer’s request.