The DON and Zearalenone Challenges Continue
The lingering effects of a challenging 2024 growing season were evident in the mycotoxin summaries across the US for corn silage and TMR samples from April 30, 2025 through September 30, 2025. While DON and zearalenone continue to be the primary mycotoxins in both sample types, Fumonisin is evident in the mid-Atlantic region. The mycotoxin summaries are presented in Table 1 and 2 and Figures 1 and 2 for the 248 corn silage and 354 TMR samples, respectively.
For the past several years, DON and zearalenone contamination have been consistently high for the northeast third of the US for corn silage, and now KS and WI are testing high for DON. North Carolina, Virginia, and Pennsylvania have similar DON concentrations as the last survey, medium to high risk, but fumonisin has increased significantly in corn silage and TMR to the high risk level.
As important as mycotoxin testing is for identifying potential challenges, the confirmation of cow performance and health is the definitive answer on the need for mycotoxin protection. The herd indicators of milk components, manure consistency, health events, and reproduction will indicate how well the cows are handling the mycotoxin load in the feed in addition to other challenge factors they are encountering. Using both the sample results and herd indicators will drive the decision determining the amount of DTX to feed. It is important to note that independent meta-analyses of Kihal et al (2022)¹ suggest that the traditional feed ingredients thought to provide mycotoxin protection are more deleterious at reducing the bioavailability of key nutrients.
Agrarian Solutions provides complimentary mycotoxin testing in feed ingredients and TMR to aid dairy producers and nutritionists in determining the correct amount of DTX is fed to support performance. Contact your Agrarian representative for assistance testing feeds and analyzing test results throughout the year.
