Kelp/Seaweed for livestock

We are considering finding some for all of our livestock.

Considering that kelp has been proven to fight viruses (prevent & treat infection), I wonder if this could be a choice way to fight all the nasties that chickens can get? Some can't even be treated with meds, are extremely contagious, and become deadly quickly. I don't want to use meds on them and the ones used to fight these bad things are only available from a vet at high prices & in large quantities, making them next to impossible to get.

Of course, we would be looking for a source in Canada.