The nutritionalvalue or quality of dietary proteins used for poultry feed formulation varies:amino acid availability is an important measure of protein quality. Determinationof ileal digestibility values has become the preferred method for estimatingamino acid availability. This review discusses the different approaches to theexpression of digestibility results, including correction for endogenous lossand the derivatisation of standardised values. Sources of variation in valuesinclude, the assay protocol, anti-nutritional factors in feedstuffs and feedmilling. Feed formulating with ileal digestibility values should allow higherdietary inclusion levels of protein feedstuffs of lower quality provided thatvalues of different feedstuffs are additive, the age of the bird and the useof feed enzymes are considered. An Australian data set of "ileal digestibleamino acid values in feedstuffs for poultry" that has recently be publishedis described. This overview is intended to stimulate interest in the generationand application of ileal digestibility as a method for estimating amino acidavailability in poultry nutrition.
