I'm not sure this is a good idea. They are in a sort of trance when they set so this interrupts. On the other hand, lots of folks are afraid they won't get up to eat, which they usually do once or twice a day, so they take the broody out of the nest. I set my 2 broodies (they are setting on air) out of the nest every time I collect eggs, because the others climb in and lay in the same nest. Most of the time they just sit where I put them, then get back on the nest after a few minutes.
I make homemade yogurt to give the girls. When we were in the 100's I added overripe bananas to it and froze for a tasty, cool treat. I have also added oatmeal and this week I began using it and warm water to soak alfalfa pellets for them
So true with the EE's! Mine are always covered in white flecks - and so am I if I don't get out of the way fast enough! I've tried it with wheat germ for them but they didn't like it as much, and also leftover smoothies but no interest in those at all. Just plain is what they like.