The impact of the protein content of feed barley on the costs of feeding beef, dairy cattle, and swine in Montana is evaluated. A model of least-cost feed rations is constructed to analyze the marginal value of additional protein content in feed barley. The results indicate that increasing the protein content of feed barley above 12% will not substantially increase the value of barley to feeders. This implies that the establishment and maintenance of a protein premium in the feed barley market would tend to result in lower average prices for feed barley because the feed value/protein relationship is concave and the market would be sustaining costs that the inherent value of the commodity could not support.