My kids have raised Cornish X 4H chicks for four years now. We have no issues with them dying, but they always seem to develop a rattle and some slight congestion for the first two weeks. Is this normal for the breed, and is there anything I can do to help them get over it? I have them on Broiler Max vitamins and electrolytes, and fresh, dry, 30% protein feed. I thought the Broiler Max may help, but they did the same thing anyway. I know there are heath issues with any bird that weighs nine lbs. in six weeks, but I wouldn't think they would have respiratory issues every time.