It is generally not recommended to add free vegetable oil in dairy rations. Vegetable oil is best provided in the form of oilseeds or animal/vegetable oil blends. If free vegetable oil is to be fed, we recommend limiting it to less than 225 grams per cow per day (0.5 lb/cow/day) to keep the unsaturated fatty acids from interfering with rumen fermentation.
Mike Hutjens, Extension Dairy Specialist, University of Illinois - Illini DairyNET
