Symmetrically substituted pyromellic diimides are disclosed wherein the compounds are substituted with a variety of substituent groups. The symmetrically substituted compounds are useful for administration to ruminant animals to increase feed efficiency, shift volatile fatty acid production in the ruminant from acetate with an increase in the more energetically efficient propionate and butyrate and to suppress methane formation in the rumen. Compositions and methods of treatment utilizing said compounds as the active ingredient thereof are also disclosed.