Use of homoarginine for measuring true ileal digestibility of amino acids in food protein

A useful application of homoarginine in animal nutrition is the determination of the true ileal digestibility (TID) of amino acids (AA) in swine complete diets and feed ingredients. The homoarginine method involves the conversion of dietary lysine to homoarginine in a guanidination reaction with methylisourea. Accurate determination of TID of AA, especially in heat-treated feed ingredients, is a key prerequisite for accurate diet formulation with respect to the provision of dietary AA. Thus, the aim of this review is to highlight the homoarginine methodology and its application in animal nutrition. Based on the data from published studies, the homoarginine method can be used to accurately determine the digestibility of lysine and the majority of other acid-stable AA in complete diets and feed ingredients fed to animals.