Abstract: The invention relates to fodder additives comprising a compound inducing the microsomal enzyme system of the liver, preferably a compound of the formula (I) ##STR1## wherein R.sub.1, R.sub.2 and R.sub.3 are identical or different and stand for hydrogen, halogen, trihalomethyl, or alkyl or alkoxy each containing from 1 to 6 carbon atoms;R.sub.4 is phenyl, dialkylaminocarbonyl or alkoxycarbonyl having from 1 to 6 carbon atoms in the alkyl and alkoxy moieties, respectively;R.sub.5 is hydrogen or methyl, or together with R.sub.4 and the adjacent nitrogen atom forms a hetero-ring having up to 8 members;n is 1, 2, 3, 4 or 5;m is 0 or 1;a is 0 or 1,with the proviso that if a=0, R.sub.1 is trihalomethyl and R.sub.2 and R.sub.3 both are hydrogen, preferably in amount of 0.5 to 99% by weight, in an admixture with conventional carriers and/or additives and optionally at least one further active ingredient conventionally used in the animal husbandry.