What the Heck Is low sugar forage replacer?

https://horse-feed-products893.evergrovio.com/posts/what-horse-feed-is-best-for-horses-with-metabolic-issues

Gentle horse feed for sensitive stomachs, designed to support gut comfort, hindgut health and better nutrient absorption. A reduced-starch high-fibre formula with naturally sourced ingredients to help maintain settled digestion and overall wellbeing.