What the Heck Is grain free performance feed UK?

https://horse-feed-brands117.tearosediner.net/what-should-i-feed-my-horse-horse-feed-guide-and-quiz-1

Gentle horse feed for sensitive stomachs, designed to support digestive comfort, hind gut health and better nutrient absorption. A low sugar high-fibre formula with natural components to help maintain steady digestion and general wellbeing.