Feed efficiency is currently a very popular topic among cattle producers and researchers. However, this is not a new concept. Researchers have been studying feed efficiency for 40 years. However, changing dynamics in agriculture have brought more feed efficiency research to the forefront. The combination of decreasing acres available for crop production, an increasing world population, increased utilization of grain for fuel, increased input costs (fuel, transportation, and fertilizer) and an increase in feed costs (grain and forage) are some of the key factors that highlight the changing dynamics of agriculture. Additionally, the recent drought in much of the United States has further reduced the available feed supply driving feed costs dramatically higher. Historically, feed costs have represented 50-70% of the cost of production for beef enterprises. As corn prices approached and exceeded $7 per bushel, feed costs were nearly 80% of the costs in many feedlot operations. In 2011, an improvement of 10% in feed efficiency in the entire feedlot sector would reduce feed costs $1.2 billion.