Because cereal grains make up 40 to 85% of most swine diets, their quality is critical. Good grain storage starts with high-quality grain obtained at harvest. There are steps that swine producers can take to ensure properly stored grain. Harvested grains should be dried to 13 to 14% moisture when stored. Grain-drying temperatures should not exceed 180 degrees F as a higher heat may result in a lowered lysine availability and an increase in the amount of cracked grain. Dried grain needs to be cooled before being stored. As grain enters the cooling bin, the removal of fines improves grain quality. Fines are often the cause of spoilage and molds. Producers should determine the temperatures in the top foot of grain in the bin to make sure that the cooling fans have adequately cooled the grain. Once grain is cooled, seal the air duct of the grain bin to prevent temperature fluctuations. These practices will help in preventing hot spots within the grain bin. An ideal grain-storage temperature is between 30 to 35 degrees F. Temperatures of 60 degrees F or higher result in mold development and insect activity. This can be caused by changing weather conditions, or from the warming of the grain during the subsequent spring and summer. Sealing the bin also helps to prevent an increase in the rodent population.