The invention relates to new carbazic acid derivatives, a process for the preparation thereof and compositions--particularly feed additives and animal feeds--containing the same. The new compounds according to the invention correspond to the formula (I)R.sup.1 .dbd.N--NH--COOR.sup.3 (I)wherein R.sup.1 stands for a C.sub.7-12 cycloalkylidene group, an indanylidene group or a group of the formula (IX) ##STR1## wherein A represents a phenyl group optionally carrying one or more identical or different substituents selected from the group consisting of halo, nitro, hydroxy, C.sub.1-4 alkoxy, C.sub.1-4 alkyl, amino or C.sub.1-4 alkoxycarbonylhydrazino; phenyl-(C.sub.1-4 alkyl), C.sub.1-16 alkyl, C.sub.3-7 cycloalkyl or indolyl, or a C.sub.3 -C.sub.6 cycloalkyl group substituted by a C.sub.3 -C.sub.6 cycloalkyl group; R.sup.2 denotes a hydrogen atom, a C.sub.1-16 alkyl or a C.sub.3-7 cycloalkyl group; and R.sup.3 represents a C.sub.1-4 alkyl group.