The present invention provides a combination of antioxidants that effectively stabilize different types of fats utilized in a ruminant diet. When included in a ruminant feed ration or water source, the antioxidant combination typically increases nutrient digestion, such as fiber and protein, improves rumen fermentation, improves microbial growth, improves microbial efficiency, increases milk production and/or milk fat, improves antioxidant status of the ruminant, and attenuates the negative effects of some fats in the ruminant animal.