How much daily food would a particularly immense unicorn need?
My character is a unicorn - not one of those MLP pony unicorns, but a true, real-life unicorn. As such, he is based on commonly accepted tropes of unicorns from
mythology history. His species is assumed to be similar to some of the largest breeds of horses.
In addition, as an individual, he is especially large and buff, with truly herculean strength. As a warrior of his culture who trains and exercises to an extreme, he is essentially the unicorn equivalent of a Schwarzenegger-level body-builder.
The character design was based on the appearance of the War Unicorns from Heroes of Might and Magic III, which have bulging, rippling muscles (especially compared to their un-upgraded counterparts) and are powerhouses dwarfed only by dragons and the like. Yet, I picture him even still somewhat more buff than this.
My assumption is that such a creature's needs would substantially exceed any real-world pet ownership suggestions for horses, due to being both larger and more physically active than most in reality. How much food and energy would this massive creature need? How does he compare to real-world equines, or to humans (to which he might adventure with)? How difficult would it be for a herbivore to actually ingest that much food daily?