What the Heck Is fibre supplement horse feed?

http://news.latestnewsfinance.com/story/609680/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 efficient nutrient uptake. A low sugar fibre-rich formula with natural components to help maintain settled digestion and overall wellbeing.