[Tomte]

And you need to trust each and every one of these people not to lie.

That's the key issue: Bitcoin works, because Bitcoins are "born" on the blockchain.

Anytime you need to relate real-world concepts to the blockchain, you need trust again. As you said: "if you trust the veterinary".

[melkiaur]

No, I think you "only" need to trust the veterinary, and make sure that all animals are tracked (which is the case in Europe, which is why the Lasagna scandal came to be a scandal). Both things are already true here.

The anti-double-spend features of blockchains is what matters after that: your cow cannot be sent to slaughterhouse 1 and 2 at the same time. Slaugher house cannot ship it to butcher A and butcher B. And it's fairly easy to check that the butcher doesn't sell it twice.

Though as I said in another comment, this can all be solved very easily if you give the DB hosting to the veterinary authorities, and very likely to be much cheaper too.