Sure but these chickens would be isolated from the outside world, like a lab setting, so how would they come in contact with something that could harm humans?
There are more things in heaven and earth, Horatio, Than are dreamt of in your philosophy.
I think there still an issue of cross contamination with things that don't grow on humans or objects, but love chickens in the air or incidental dusts.
Until one day that security setting breaks down.