Researchers compared hair samples before and after the changed diet. Microscopic photos showed a smoother surface on the hair as a result of feeding the chelated minerals. Supplementary feed traditionally has been oil-based. Horsemen used to rely on oils, such as linseed oil or corn oil. Now the fat used is rice bran.
Soybean meal is another source of fat used in commercial products.
Hair coat supplements such as Mirra-Coat and Shine 'n Win Hair Coat Enhancer list soybean products in their formulations. Linoleic acid, an unsaturated fatty acid, contributes to the production of sebum. However, too much fat can be detrimental. Fat supplementation might not benefit the coat, as cited in the textbook Equine Clinical Nutrition . Author Lon Lewis reported research that detected no changes in skin, hair coat, or hooves of two groups of ponies.