The folks as Tikkun Farm feed their Alpaca autumn leaves.
Consistent nutritional value information might be hard generate, if it's important.
If you liquify the green leaves by blending them down, you could dry them out into flakes or powder.
Low temperature and no direct sunlight to maintain nutrients.
Maybe mix with autumn leaves to help dry it out and add bulk,minerals and texture.
Biochar is another admixture that could add value.
Willow, mulberry, maples or box elder,sunflower or j choke stalks, apple or pear, morninga, are all nutritious possibilities.