Burt Weichenthal

Nutrient Values of Spring and Summer Annual Forages in a Single Cut Harvest1

Abstract The Central High Plains of the United States (western Nebraska and Kansas and eastern Wyoming and Colorado) is a major beef cattle production area, but it is subject to periodic droughts. Annual forages are an essential feed source for maintaining beef cattle herds during periods of drought and winter months. The objective of this study was to determine nutrient concentrations in annual forages, including barley, oats, triticale, forage sorghums, sudangrass, pearl millet, foxtail millet, field peas, soybeans, and vetch grown for hay in this region. The summer annuals—forage sorghums, sudangrass, pearl millet, and foxtail millet—were grown in replicated rain-fed and irrigated trials whereas the other forage species were grown in only rain-fed trials. Currently available cultivars of these forages species were included in the trials that were located primarily at Sidney and Scottsbluff, Nebraska. Results demonstrate that the harvested forage of many of these species approached or exceeded 10, 60, 0.4 and 0.2% of CP, TDN, Ca, and P, respectively, exceeding diet composition requirements for growing beef cattle and gestating beef cow classes listed by the NRC. Nitrate-N values exceeded safe feeding levels in pearl millet and irrigated foxtail millet forage, probably due to high soil N fertility levels. Feed testing of warm-season, summer annual forages grown in this region for nitrate-N would be a prudent management practice.