Experience has shown that a ratio of omega-3 to omega-6 fatty acids of 1:3-5 is recommended for optimal health. While omega-3 fatty acids predominate in hay and fresh grass, the ratio of fatty acids in cereals is 1:20 to 1:30 (!), resulting in a significant overweight of omega-6 fats with all the negative consequences that entails. Therefore, an oil with the highest possible omega-3 fatty acid content and the lowest possible omega-6 fatty acid content should be added daily to optimize the fatty acid profile, especially for horses that are fed concentrated feed. Of all the vegetable oils used in horse feed, linseed oil is by far the most suitable for this purpose.