The growing global population, changing climate, and decreasing resource availability create a need to improve efficiency and durability of food production. Within the current US food production system, dairy products play an important role in providing high quality protein from human inedible inputs. The environmental impact of dairy products is lower than many other animal products and several non-animal derived foods; however, greenhouse gas emissions and N and P runoff from dairy operations should be minimized wherever possible. Enhancing energy and N use efficiency of dairy cattle production will reduce these environmental impacts and potentially improve farm economic viability. In current systems, gross energy and N are converted to milk energy and N with approximately 20% and 25% efficiency, respectively. Phosphorus capture in milk is slightly greater at 40%. Gains in energy efficiency occur with increasing production through dilution of maintenance costs; however, there are opportunities to improve energy efficiency through enhanced digestive action or improved metabolic efficiency. These will reduce methane emissions. Experimental evidence suggests ample opportunity to enhance N use efficiency. The rumen can be operated above 100% apparent efficiency by feeding low N diets and forcing greater reliance on blood urea yielding a potential improvement of 5% units in efficiency. Postabsorptive N efficiency is approximately 35% and the upper limit is probably as high as 70%, which suggests potential of improving by an additional 10 to 20% units. The latter requires enhanced knowledge of amino acid metabolism. Gains in the efficiency of P utilization will likely require significant improvements in our basic understanding of the regulation of P metabolism. The digestive tract generates excess quantities of absorbable inorganic P suggesting the current limit is not one of digestibility. There are additional opportunities associated with the use of feeding technologies and facility designs that can tailor diets for individual cows based on current and projected production and their genomic profiles, sense and respond to variation in feed inputs, and alter rations to mitigate environmental stress and variation.