Dr. Kenneth I. Shine is president of the Institute of Medicine. The National Research Council was organized by the National Academy of Sciences in 1916 to associate the broad community of science and technology with the Academy's purposes of furthering knowledge and advising the federal government. Functioning in accordance with general policies determined by the Academy, the Council has become the principal operating agency of both the National Academy of Sciences and the National Academy of Engineering in providing services to the government, the public, and the scientific and engineering communities. The Council is administered jointly by both Academies and the Institute of Medicine. Dr. Bruce M. Alberts and Dr. William A. Wulf are chairman and vice chairman, respectively, of the National Research Council.
Nutrition is a key factor in the perfor- mance, health, and welfare of dairy cattle.
Given the large variation in dairy cattle types and the various environments in which they are maintained, producers must increasingly concern themselves with optimizing feeding programs. As we conducted our work, it was our desire to provide users of this volume an accurate, comprehensive, and useful review of the scientific literature and practical experiences that have shaped our knowledge of dairy cattle nutrition over the past decade. We chose to provide both a written description of the biologic basis for predicting nutrient requirements and a computer model on a compact disk to use for estimating requirements of lactating, nonlactating, growing, and young dairy animals. The subcommittee recognizes that some users of this revision will prefer to apply tables of requirements for an average situation, and we have attempted to provide those tables. Although there is often uncertainty using a modeling approach to estimate nutrient requirements, we believed that we had a responsibility to move the science forward, so we included a model that was constructed on a substantial amount of data.