I wanted to put this question up for discussion and see what everyone's views are on this subject.
I don't really use manure. When I started gardening, I bought the bagged manure at big box stores. I once left one bag out too long and it stank like ammonia, and that turned me off.
When I started composting I revisited the idea of manure again because almost every composting instructions talk about manure like an essential ingredient. But living in a subdivision and working 12 hr days made it difficult to stop at any of the horse farms along my commute, though I considered it many times. This was before the days of ready access to Internet advertising like free cycle and Craigslist -- recommendation was to check the message boards at the feed store.
When I became interested in learning to ride, I did being a few buckets of composted and fresh horse manure home... Until I really got into horse are and learned that the horses are "wormed" regularly. Then I started thinking about livestock care in general, and learned that "worming" is essential for all hoofed livestock. So I looked up ivermectin because I wondered if it passed into the manure and if it affected earthworms..... Then I started thinking about other meds/pharmaceuticals that are regularly given to livestock. (There was one horse at the stable that was regularly fed something "to keep her calm")
A couple of years ago, I learned that there is a rabbit rescue not too far away, and considered getting rabbit cage bedding from them, but never got around to it,
I'll stop here because I'm not that knowledgeable about this. Just bits and scraps of information gathered here and there and I haven't come to any real conclusion. Mostly not using manure because it's more trouble than I'm really willing to go through to get them, and, so far, not using it in my gardening repertoire hasn't made me think I really should make the effort.