Abstract
The comprehensive studies of energy metabolism by the research team of Nehring, Schiemann, Hoffmann, Jentsch and Chudy at the Oskar Kellner Institute of Animal Nutrition at Rostock, Germany, during the past 14 years were summarized. The new system of feed evaluation and nutrient requirements as developed on the basis of Kellner's net energy concept was explained. Contents of the net energyfat (NEF) in purified nutrients and feeds from many different groups had been determined in several hundred respiration trials by the difference method. It was found that NEF can be calculated from contents of digestible nutrients with the same accuracy as by direct determination in respiration experiments. The obtained regression equations can be used without restrictions only in monogastric animals. For ruminants, because of interactions between the basal ration and supplements in the rumen, the difference method was replaced by an evaluation of whole rations, including 92 rations with cattle and 81 with sheep. Final regression equations and standard deviations gave satisfactory accuracy of NEF values for all feeds and all farm animals. Differences between animal species indicated that values cannot be transferred from one species to another directly. Equations for the calculation of gross energy, digestible energy and metabolizable energy from nutrient contents were developed. Examples of calculations of rations from the tables of feed composition and nutrient requirements were given. Tables list values for three groups of animals separately: ruminants and horses, monogastric mammals, poultry. Parameters of calculations are kcal NEF, g digestible crude protein, kcal EF (energy feed units) per kilogram dry matter and EPQ (energy-protein quotient). Copyright © 1973. American Society of Animal Science . Copyright 1973 by American Society of Animal Science.