What the Heck Is horse feed for weight gain?

https://comobuz.com/online_features/press_releases/in-the-home-of-endurance-racing-bifid-brings-grain-free-gut-first-feed-to-the/article_3ecceb11-0df6-5451-92da-d7c77d0247f8.html

Liquid horse feed supplements support hydration, digestive health, and daily nutrient balance for performance horses and pasture horses alike