Thankfully I'm starting mine early. My oldest is 2 1/2. To her, when one of the chicks doesn't make it the chick is "broke." She's "broke" rodents, rabbits, baby birds, etc from the cats, and the periodic chick that doesn't make it.
Our broilers are 4 weeks old. She doesn't know the difference. They're all chicks to her, and we have enough that I don't think it will matter, even when she's older, that they're disappearing.
Not naming them is a huge thing! We don't name livestock around here, and my chickens are definitely livestock.
I picked up a bunch of chicks last week at the PO. A little girl walked in behind me and asked to see them. I peeled back the corner of the box to show her. She asked me if they all had names yet! It was very cute, but my vocal response was "not yet." My unspoken response was "dinner" LOL
Kendra
PS I'm hoping that as my girls get older they're so used to the process that it won't be an issue. We also breed dogs. Life and death is part of the process. I'm hoping to instill some natural respect for that. I've never butchered anything before. I'm forcing myself to help the neighbor butcher our chickens for the same reason.