Any reason why the broody hen pecks the chicks. I can understand the past is a good indicator of the future. What I'm more of asking is if the hen can smell the true laying hen and somehow know they aren't hers or something else that would make her hate the chicks she just spent over 2 weeks hatching.
I don't know if this could be a related thing or not, but with rabbits you sometimes have a doe that eats the kits she just gave birth to. It's my understanding that this usually indicates a protein deficiency. Some people give their doe a few slices of hotdog the day before she's expected to deliver to help prevent this. We've only had one doe eat her kits & by the time we discovered she was doing it, it was too late... Could this possibly be what might be going on with the hen -- she's needing the extra protein? It's kind of hard to imagine as humans that a new mom would do this, but in the animal world they're just responding sometimes to the needs of their bodies...