The present invention belongs to the field of feed, and particularly relates to a feed additive containing biogas residues for cows. The feed additive for cows is prepared by mixing the following components in parts by weight: 20-50 parts of biogas residues, 15-28 parts of radix astragali residues, 10-12 parts of apple pomace, 3-6 parts of purple perilla, 4-8 parts of eucommia leaves, 3-8 parts of purslane and 0-1 part of maca powder. The biogas residues are resulting products from anaerobic fermentation of distillers' grains left by using cassava or sweet potatoes as raw materials for fermentation, and are then moisture removed by mechanical extrusion, dried by exposure to the sun and finally crushed by a crusher for use. The scientifically-formulated and nutrient-rich feed additive provided by the present invention enhances the immunity of cows, decreases the risk of various diseases or infections during the feeding process, and reduces the use of drugs. The accumulation of active substances of the raw materials in cow tissues also improves the milk yield.
