I'm looking to expand my garden next year and I will need a lot of manure for that,so i'm looking to make my own manure and I need a little advice
Horse manure is good , but be sure that it's composted well enough to kill weed seeds because horses don't digest whole seeds well.
~Martin
Depends on what the horse are fed.....the biggest potential threat is hay that may have something like bindweed seeds in it.....the seeds may survive composting and it's almost impossible to get rid of.
~Martin