Prime ESE Plus contains a combination of vitamin E, selenium, and DMG. Vitamin E is an essential nutrient for horses that plays many important roles in the body. It is a powerful antioxidant that helps to protect cells from damage caused by free radicals. Selenium is a mineral that works with vitamin E to support the immune system and promote healthy muscle function. DMG is an amino acid that supports the immune system, promotes oxygen utilization, and improves stamina and endurance in horses. For more information, visit http://www.primeperformancenutrition.com/