Molds are fungi (fuzzy or dusty – appearing) that occur commonly in feedstuffs, including roughages and concentrates. Molds can infect dairy cattle causing a disease referred to as mycosis. Mycosis is most likely when cows may be immune-suppressed during stressful periods. A mycosis can occur in various locations such as lungs, mammary gland, uterus, or intestine. An intestinal infection may result in hemorrhagic bowel. Molds may also affect cattle by producing poisons called mycotoxins that affect animals when they consume contaminated feeds, resulting in a mycotoxicosis.