The value of commodity feeds is well established in the beef cattle industry. An often-overlooked aspect of supplementing grazing cattle with hay is the additional mineral nutrients that pass through the animal to the pasture in the manure and urine. The objective of this guide is to help calculate the value of supplemental feeds as a fertilizer for pastures. With manure nutrients, cattle are the fertilizer spreader. Urine typically contains more than 50 percent of the total nitrogen and potassium excreted by cattle. Conversely, feces contain 80 percent of the total phosphorus excreted by cattle. The nutrients in supplemental feed are only valuable as a fertilizer if you take steps to ensure that they are spread evenly around the whole field. Animals typically do a poor job of distributing nutrients around a pasture; nutrients tend to concentrate near feeders, water and shade areas. The bulk of the pasture often gets only limited benefits from manure nutrients unless steps are taken to improve manure distribution by grazing animals. Download from Univ. of Missouri Extension website here.