Oil-seeds and high-protein seeds are rich in protein and in energy; their fats generally contain large amounts of polyunsaturated fatty acids which are beneficial to human health. All these seeds however undergo a rapid degradation of their proteins in the rumen, bringing about a waste of nitrogen and but a marginal utilization as a source of nitrogen in the feeding of ruminants. How to reduce the degradability of proteins is known, but the applications are limited in view of the omnipotence of soybeans. Improvements by breeding are possible, but are not yet evaluated. In practice, a solution is found in the form of the presentation : the feed should be given whole or very roughly flattened rather than finely ground ; this is a simple way of protecting the proteins, and its efficiency is proved. It should be optimized and its impact on the nitrogen value quantified. Thermal treatments exist aplenty, but those that, in France, have gone beyond the stage of the pilot plant are rare, except extrusion and the heat treatments included in the oil-extracting processes, which give cakes as a by-product, the nitrogen value of which is vastly superior to that of the initial seeds. We have ranked these various thermal treatments (torrefaction, toasting, extrusion) according to their efficiency in increasing the proportion of treated feed proteins that escape ruminal degradation, independently of their cost. The processes used in oil-mills appear to be easily adaptable ; the chemical treatments are just mentioned in their principles.