Horse manure if composted right. It takes about a year. The piles need to be large enough and need to sit for about six months or until the center starts to heat enough to kill off the bad stuff. This will also kill the seed that passes through. You do need to rotate the pile, and can wait another 6 or so months. There is a peat like structure when its done, and most of the minerals, etc. will still be there. Bonus....doesn't smell anymore, except like rich soil. You city folks and such may have to sneak in a mini-horse or two. They are very lovable.

Oh,...cat crap is nasty stuff. So are pigs, people, & dogs. No offense meant there, all very lovable creatures, but the crap is full of nasty surprises.