The chemical composition and structure of dietary fiber, as well as physicochemical characteristics such as bulk density, swelling, water binding capacity, and viscosity, may influence the digestion of energy and nutrients in feed ingredients. Having a complete account of the components of a feed ingredient, particularly the type and concentration of fiber, is necessary in order to accurately the energy value of an ingredient using prediction equations.

An experiment was conducted to obtain a detailed description of the composition of ten feed ingredients, and to compare the analyzed gross energy (GE) with the GE predicted by adding together the measured energy-containing components. A secondary objective was to measure the in vitro apparent total tract digestibility (IVATTD) and in vitro apparent ileal digestibility (IVAID) of dry matter (DM) and organic matter (OM) in the feed ingredients, and to determine the correlations between the physicochemical characteristics of the ingredients and the in vitro digestibility.