Digestive and Metabolic Utilization of Feed Energy in Swine: Application to Energy Evaluation Systems

Abstract

Noblet, J. 2000. Digestive and metabolic utilization of feed energy in swine: Application to energy evaluation systems. J. Appl. Anim. Res., 17: 113–132.

Feeds can be attributed different energy values according to, first, the step considered in energy utilization (DE: digestible energy, ME: metabolisable energy and NE: net energy) and, second, the method used for estimation at each step. This paper reviews some of the most important dietary (chemical composition) and animal (body weight) factors which affect digestive and metabolic utilization of energy by pigs. Available results show that energy digestibility is negatively affected by dietary fibre (DF) content of the diet and is increased with pig body weight, the negative effect of DF is reduced in heavier pigs, so that most feeds should be attributed at least two different DE values, one for growing-finishing pigs and other for mature pigs (reproductive sows). Metabolic utilization of energy is highly related to diet chemical composition with higher efficiencies for ME provided by fat or starch. The hierarchy between feeds is then dependent on the energy system, with a clear preference for NE systems which are the best predictors of the “true” energy value of feeds and of performance of pigs. The available NE systems are also compared. Further improvements of energy systems for pigs are discussed.

Key words:

• Feeds
• pigs
• energy value
• energy system
• digestibility
• heat production
• digestible energy
• metabolizable energy
• net energy