This statement is a comprehensive presentation of the scientific arguments and aspects relevant to practical feeding and formulation of rations and compound feeds which are important in evaluating feeds for pigs on the basis of metabolisable energy (ME) and net energy (NE).
The ME indicates the capacity of a feed to provide energy for the animal’s metabolism. The NE additionally includes the nutrient-specific heat losses occurring in the metabolism and represents the retained energy (RE) in the growing animal. However, because the extent of these losses is not constant, especially for protein, and the energy requirements for basal metabolism, gestation, thermoregulation and physical activity must be expressed as equivalents to RE, this leads to problems or inaccuracies. The RE as part of performance prediction is therefore only partly successful with a NE system. Only by knowing the composition of the ration, especially its protein and amino acid contents, and the animal’s characteristics, notably protein deposition capacity, is it possible to predict growth, body composition and nutrient excretion.