What the Heck Is low sugar forage replacer?

http://www.madisonheadlines.com/news/story/582403/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, hindgut health and easy nutrient absorption. A low-starch fibre-rich formula with natural ingredients to help maintain calm digestion and overall health.