What the Heck Is grain-free horse feed UK?

http://www.georgianewsdesk.com/news/story/560527/with-half-of-britains-horses-overweight-bifid-launches-grainfree-lowsugar-feed-for-the-nations-gooddoers.html

Gentle horse feed for sensitive stomachs, designed to support gut comfort, hind gut health and easy nutrient absorption. A reduced-starch fiber-rich formula with natural components to help maintain steady digestion and overall health.