The sustainability of livestock is perhaps best represented by the ability of cattle to process potential waste products and turn them into nutrient-dense milk and meat. Often forgotten brewers grains and distillers grains, which are the leftover waste products from brewing beer and producing ethanol, provide protein, fiber and energy to cattle forage. In fact, the energy value from these grains can be 85% to 95% that of corn grain. While the waste products make an excellent feed addition, the high-moisture content can lead to rapid spoilage. Producers using leftover grains are encouraged to use three-walled concrete structures to prevent runoff and leachate.