After 10 trouble free weeks with these birds, this am I found 3 dead birds practically under the roost. The only thing that has changed recently was the addition of two bags of coarse pine shavings added to the floor day before yesterday. These birds showed no injuries other thean feathers pulled which I assume the other chickens did to the corpses. They were raised for over 5 weeks on shavings without problem, so I assumed it wouldn't be a problem now. They are on TSC chick starter, plus they get a couple cups of scratch grain per day. I've added some tetracycline to the water as a precaution. Anyone else have a comment or idea?