I was not aware that the issues surrounding manure went far beyond antibiotic contamination. This link highlights an emerging problem surrounding what happens to the manure of horses that consume hay that has been treated with a herbicide called aminopyralid, and how this manure can ruin your soil for growing food for years.
http://www.guardian.co.uk/environmen...od.agriculture
In organic circles we used to recommend getting free-by garden supplements like manure as a way to enhance soil fertility. This article and the discussion currently going on in general about how people's tomatoes got destroyed after using tainted manure highlights how cautious we must now be these days about what we use in our gardens.
Stacy