If levels are still elevated after ensiling, amounts may have to be limited in rations. Forages most likely to be a problem are plants in the sorghum family and corn for silage. Corn for grain is not a problem because nitrates are in the stalk not the ear. Aflatoxins could be a concern. Dr. Dennis Blodgett of our College of Veterinary Medicine says that the critical time for aflatoxin formation is at time of silking.
Dry years are the worst for aflatoxin contamination in corn.
He recommends checking the silage, not just the ear, when looking for presence of aflatoxin. Rations should contain less than 20 parts per billion. Levels of 30 parts per billion can cause residues in milk. It is possible to feed bentonite or activated charcoal to bind toxins in the gut to prevent absorption. However, this may not prevent detection of residues in milk if high levels are in the feed.