What the Heck Is fibre heavy performance feed?

http://www.hartfordnewsreporter.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 digestive comfort, hindgut health and better nutrient absorption. A low-starch fibre-rich formula with natural ingredients to help maintain settled digestion and overall wellbeing.