This Feed Safety Series comprises a series of compact guidebooks on various aspects of animal and human nutrition. The objective is to provide comprehensive scientific information of value to nutritionists, students, feed manufactures and other professionals working in nutrition, in a modest sized book. This first volume deals with moulds, which are a constant threat to feed supplies and to animal and human health. The classification of moulds and their growth requirements is explained and there is a thorough discussion of the damage that moulds can cause to feedstuffs and health problems that may arise. Methods of assessing moulds in the laboratory are briefly presented followed by strategies and procedures to control mould growth. Finally some beneficial effects of moulds are discussed.