The present invention relates to a method for reducing the production of methane emanating from the digestive activities of a ruminant and/or for improving ruminant animal performance by using, as active compound at least one organic molecule substituted at any position with at least one nitrooxy group, or a salt thereof, which is administrated to the animal together with the feed. The invention also relates to the use of these compounds in feed and feed additives such as premix, concentrates and total mixed ration (TMR) or in the form of a bolus.