Minimizing excess crude protein levels in the feed by formulating to balanced levels of digestible AA, rather than to minimum crude protein levels, will minimize nitrogen excretion. The sub-section on Protein and Amino Acids fully explains the concepts of ideal AA profile and balanced protein, which can be used to reduce nitrogen excretion. Recent work has helped to add quantitative information to the extent of reductions in excretion. For example, it has been determined that a one-percentage point reduction in feed protein level (e.g. from 20% to 19%) results on average to a reduction in both nitrogen excretion and ammonia emission of 10%.