I'm new to raising chickens but i did a lot of research before purchasing chicks. I went to our local chick hatchery and got multiple types of chickens. In this group I purchased 4 partridge cochin chicks and they have all died. They have died, one at a time. The chick will start just standing under the light staring at the wall, about an hour later it's laying in the floor of the brooder heavy breathing. It starts opening and closing its beak until it dies. They are all eating and drinking and the temp in the brooder is around 92 degrees. So far this has only happened to the cochins. I also bought 4 silkies, 2 polish, and 2 japanese bantams and they are all doing just fine but I'm terrified that this may be something contagious and that this will spread to the rest of the chicks! I called the hatchery and all they said was for me to put apple cider vinegar in their water. Anyone have any idea what has happened to my babies?