Mycotoxin Survey in US corn: December 2019 update

Our December update kicks off our annual Biomin® PROcheck mycotoxin survey in corn harvested in 2019. Results are still preliminary due to the delay in this year’s harvest resulting in reduced sample numbers thus far, and our understanding of this harvest year’s risk will likely shift drastically in the coming months. Currently the sample pool includes 129 samples from 18 states. This year clinical cases were excluded from the analysis, thus survey results represent samples of corn sent in for surveillance testing only. Of the sample pool 68% are corn samples (88 samples), 8% are corn by-product (10 samples), and 24% are corn silage (31). Of the total sample pool 96% tested positive for at least one mycotoxin vs. 98% in 2018, while 61% of samples had more than one mycotoxin compared to 74% in 2018. Below we discuss preliminary trends of each of these feed ingredients regarding mycotoxin prevalence and contamination levels. 

Corn 

  • 95% of ground corn samples are positive for at least one mycotoxin, vs 98% in 2018
  • 64% of samples have more than one mycotoxin, vs 73% in 2018
  • Aflatoxin prevalence in dry corn decreased to 2% vs 10% in 2018, with average contamination levels decreasing significantly.
  • Prevalence of type B-Trichothecenes (such as deoxynivalenol, also known as vomitoxin), fumonisin, and zearalenone all maintained prevalence and contamination levels similar to last year. 
  • Overall, challenges seem very similar to last year with variation from region to region.

Corn By-Product

  • Although there are limited sample numbers, consistent risk from type B-Trichothecenes, fumonisin, and zearalenone has been observed.
  • Nivalenol, a type B-Trichothecene more toxic than deoxynivalenol has been consistently observed in DDGS (data not shown). This is likely from 2018 corn.

Corn Silage

  • 97% of samples are positive for at least one mycotoxin, vs 93% in 2018
  • 42% of samples have more than one mycotoxin, vs 66% in 2018, representing an improvement in co-contamination prevalence. This is still above 2017 levels (27%).
  • Aflatoxin prevalence negligible in this sample pool, but producers in Southern regions should still be vigilant of aflatoxin risk.
  • Type B-Trichothecene prevalence has increased slightly to 97% vs. 93% in 2018, with similar contamination levels.
  • Fumonisin prevalence and contamination levels have decreased to 6% vs 22% in 2018, with average contamination levels dropping 8-fold.
  • Zearalenone prevalence decreased to 39% vs 55% in 2018, with average contamination level decreasing by half.

These contamination levels present MEDIUM to HIGH risk for all livestock and poultry species depending on toxin and feed ingredient type. The risk profile of 2019 corn is currently highly dynamic due to the number of samples. Overall, producers in the Midwest should be on the lookout for the impacts from deoxynivalenol and zearalenone, while Southern states should be vigilant regarding fumonisin and aflatoxin contamination.