Abstract: A novel feed supplement for ruminants containing lipids which are dispersed within a protective protein-aldehyde complex is provided. The protective protein-aldehyde complex which is substantially insoluble in the rumen but soluble in the abomasum and lower gut of a ruminant, protects the dispersed lipids from breakdown within the rumen. The feed supplement is produced by a process wherein a protein and lipid mixture is contacted with a sufficient quantity of an aldehyde, while being subjected to higher than atmospheric pressure and elevated temperatures during an admixing and comminuting operation such as within an extruder, to form the protective protein-aldehyde complex. The material, when extruded in an agglomerated form, produces a feed supplement for ruminants.