Compositions for reducing the emission of methane by ruminant animals are disclosed. The compositions include avian antibodies against methanogens generally found in the rumen of the animals. Egg contents of eggs from female birds inoculated with immunogenic compositions containing one or more methanogens or antigens derived from methanogens are used. The antibodies in the egg contents may be used directly without further purification, may be partially purified or purified. The compositions may be administered in drinking water or in animal feed. Administering of the anti-methanogenic composition reduces the emission of methane and increases the efficiency of feed conversion.
