That seems unreasonable. Domesticated animals are raised by us to be killed. The moment we raise them with the intent to butcher them, we are asserting that they are our food... and food and drink are typical offerings. If, and let me emphasize, *if* I were to sacrifice an animal however, I would try and purchase an animal that was already going to be butchered, and treat it as well as possible while raising it. Again, that's a big"if", since I lack the resources to do this, but I think in general, there would be a correct way to go about it. It would be difficult, but not impossible. As a matter of fact, this is legal for the freedom of religions such as Santeria.
Animals get killed everyday, we eat them, I get that. But leaving it as an 'offering' to me is pointless killing. Politically speaking Animal offering is very vague, and the laws vary according to city. a few years ago in my city for example, a lady was arrested because she was sacrificing goats and leaving them to rot.