Energy evaluation systems for pig diets

Abstract

Different energy values can be attributed to a given feed according, firstly, to the considered step of energy utilization by the pig (digestible (DE), metabolizable (ME) or net (NE) energy) and, secondly, to the prediction method used for each step. The aspects developed in the first part of this review relate to the effects of chemical composition of the diet and animal factors such as age or body weight on digestive and metabolic utilization of energy. In a second part, the available DE, ME and NE systems when applied to diets or ingredients are presented. In the third part, the different energy systems are compared in terms of advantages, limits and applicability for each of them. The comparison indicates that the hierarchy between diets and, more clearly, between ingredients and, consequently, results of least-cost formulation are dependent on the energy system.