I have only heard of large quantities of stuff in a single mass spontaneously combusting.
While 200 pounds of poo is a 'large quantity' in my book,
and I want 200 pounds of alpaca poo,
I suspect the fact that it's bagged would interfere with it heating to burning hot?
I've read that you can use it directly on the garden like rabbit manure, although there's the parasite thing.
here's a thread that talks about it.