The purpose of this book is, "To present the principles of nutrition and their applications to feeding practice." Over the past years, nutritional science has been moving forward at an ever-increasing pace. Additional essential trace elements have been discovered and, of more importance perhaps, our knowledge has been greatly enhanced. This enhancement reflects the epoch-making discoveries in cellular metabolism made by the biochemist, which have produced more precise information regarding nutrient requirements, not only to prevent physical signs of defiency, but also to ensure the normal functioning of the various body processes concerned. In the present edition an attempt has been made to portray these developments and point out their significance in feeding practice.