Utilization of the L- and DL- isomers of α-ketomethylvaleric acid by chicks

Abstract A chick growth assay was conducted to determine isoleucine-replacement values of the L- and DL-keto analogs of isoleucine (i.e., ketomethylvaleric acid, KMW). Chicks were fed a chemically defined isoleucine-deficient diet containing increments of L- isoleucine (Ile), L-KMV or DL-KMV. Based on slope-ratio methodology, the utilization of L-KMV and DL-KMV relative to L-Ile were 78.9 and 41.5%, respectively. This indicates that the chick can obtain roughly 80% L-Ile activity from L-KMV and that D-KMV is biologically inactive.