I am so sorry! This has also happened to me. A lot of the time I think it's just first time motherhood. They get threatened, and it's pretty easy to stomp on their babies to death (or pick at them to death) very horrifying. Some people may disagree with me, but I don't think day old chicks should go down a ramp--even if they are with their mom. I've seen chicks get rolled down the slight ramp & stomped on by mom. Ouch. I know it's survival of the fittest--- but harsh!!!
I have Silkies, and most of them are very sweet, wonderful broodies--- but only one is a good mother to her chicks. I use the others just to sit on the eggs-- then use my main mom for the crucial hatch time. Even the best hen is not very patient after a week or so, and in the past I have confined her to a small hutch inside my garage from day 18 to about day 23 until she hatches all she can. Slowly, I start taking the newborns out of her hutch and into a brooder nearby. The strongest chicks stay with her for a few days & she doesn't even notice the newborns are gone. It's their natural instinct to neglect any sick or damaged chicks, so if I didn't take out the "questionable" ones, they would have been left for dead.
Maybe my hens will change with more experience (they've only hatched a couple of times) but I have found small hutch + brooder technique works for me. Oh, and I just set more eggs today---this time in the incubator!
Hope this helps!
