There seems to be some studies showing that it reduces salmonella uptake in broilers, but beyond that I haven't found anything (and salmonella isn't really a big issue in small flocks). The reduction in salmonella seems to be caused by increased mucus production in the digestive tract, so I'm not sure that's a good thing.
Beyond that I wasn't able to find much beside a whole bunch of 'natural' websites promoting it, but offering no actual support for their claims.
So then skip it? I am guessing you do not use it?