I looked online at the label for that product. The label refers to the material as a compost, but the name does imply that it's farmyard manure (as a vet, I can see why you would be expecting a different product).
The back label refers to something called the Growing Media Initiative (they seem to have a website), which sounds like a trade organization or council of some type, that may set standards, or at least may be aware of established standards. That might be a place to start looking for information on applicable regulations.