Automated analysis of available lysine and tyrosine in foodstuffs

Abstract
An automated chromatographic procedure for FDNBa‐available lysine determination is presented. “Available tyrosine” values can be obtained from the results and it is suggested that measurement of 100% tyrosine availability is a useful control for complete reaction of feedstuffs with FDNB. Application of the method to a range of feedstuffs confirmed the high availability of lysine in commercial feedstuffs. Using the tyrosine availability figures as a control, it is suggested that low values of lysine availability for fishmeal and meat and bone meal are an artifact but that grassmeal contains incompletely available lysine.