A mycotoxin produced by Penicillium moulds, including Penicillium roquefortine. It is a neurotoxin and causes a lack of coordination and muscle weakness in animals that have ingested it. Patulin reduces the production of volatile fatty acids in ruminants, reducing the amount of energy a cow is capable of obtaining from its diet. Patulin is commonly found in silage so is classified as a silage mycotoxin.