About three weeks ago, I went to a local feed mill that sells day old chickens. They had five black australorp pullets which we bought. Brought them all home and they are all growing well, but one has always been a runt and as the others are growing, this one is lagging behind and the size difference is growing each week. Now that they are almost four weeks old, the others are almost twice as big as this one. I picked her up tonite and checked her butt which was clean and not clogged up or anything. She doesn't peep as loud as the other ones, and when she breathes it looks like she is laboring to do so, but that may be a concerned parent looking for something wrong. I filled up their feed tonite and she went over with the others and started eating and noone picked on her or kicked her away. I also have two feeders so there is plenty of space so that she isn't getting forced away from the feeder by the others. Could there be something else wrong with her, or is she just a runt in the bunch? Thanks for any help.