The use of a feed supplement to improve the feed utilisation of a ruminant where said feed supplement is prepared by reacting a prepared precursor, which contains organic acids, with a multivalent cation source to precipitate a reaction product, where:—the prepared precursor is prepared from a plant precursor selected from the group consisting of an undried fermentation by-product, an undried fermentation product, undried acidic plant material and an undried pomace； and—the prepared precursor contains C3/C4 organic acids.
