What the Heck Is low starch feed for horses?

http://www.montpelierjournal.com/news/story/555500/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 digestive comfort, hind gut health and better nutrient absorption. A low-starch fibre-rich formula with natural components to help maintain steady digestion and overall health.