Abstract: The growth rate of an animal is stimulated by administering to the animal a growth promoting amount of a compound of the formula ##STR1## wherein R.sub.1, R.sub.2, R.sub.3, R.sub.4 and R.sub.5, which can be the same or different, are each selected from the group consisting of hydrogen, alkyl having 1 to 4 carbon atoms, alkoxy having 1 to 4 carbon atoms and halogen; X is selected from carbonyl and a ketal group of the formula ##STR2## wherein R.sub.6 and R.sub.7, which can be the same or different, are each selected from hydrogen and alkyl having 1 to 3 carbon atoms; A is a linear or branched alkylene having from 1 to 8 carbon atoms; and R.sub.8 and R.sub.9, which can be the same or different, are each selected from the group consisting of hydrogen, alkyl having 1 to 4 carbon atoms, or 2-hydroxy-alkyl wherein the alkyl group has 2 to 4 carbon atoms, or R.sub.8 and R.sub.