Ground feed is an ideal source of food for fungal growth. Corn screening are excellent media for fungal growth and have been associated with Fumonisin toxicity. The time between harvest and drying is critical. That's when temperature and moisture conditions are often ideal for mold growth and toxin production. Consequently, do not delay drying grain for more than 6 hours and dry grain to recommended moisture levels.
Storage conditions are also important.
Grain storage bins should be clean and in good repair. After drying, cool the grain to air temperature before loading the storage bin since hot grain can cause condensation, which sets the stage for mold growth and toxin production. Feed and grain storage bins should be cleaned at frequent intervals to prevent bridging of feedstuffs and formation of hot spots. Consider treating the grain, after drying and before storing, with an insecticide to reduce insect damage. Fungal inhibitors, such as propionic acid, may be effective in preventing fungal growth on stored grains.