What the Heck Is low-starch horse feed?

http://www.harrisburgnewsnow.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 comfortable digestion, hind gut health and efficient nutrient uptake