I have a brood that is almost 3 weeks old and I've had two sudden declines and that resulted in death. The first I found last week and it was weak and listless and it died a few hours later. I'd tried to nurse it with some Save a Chick Electrolytes. The second death happened yesterday when I found a Welsummer dead in the brooding area. I check on them about 5 times a day as I work here on the farm at home and neither have showed any symptoms leading up to death, ie no slow decline. The have clean water, plenty of chick crumbles, pine litter that is clean in an insulated, but cool, well ventilated room with the heat lamp going. There are 23 chicks in an 8 x 6 foot pen. Any suggestions as to what might be causing these deaths or things I could do to prevent more? Thanks!