I have successfully brooded standard size chicks numerous times with a 1% loss rate.. I recently purchased 50 bantam chicks of mixed breeds. I purchased from a reputable hatchery so I'm sure the chicks were handled well. Sadly, I have lost 15% in the first 4 days. The bantam chicks were purchased with 75 regular chicks and I have had no losses in the regular chick brooder . . . the bantum brooder is another story. I picked the chicks up at the hatchery and drove straight home so I'm sure travel temps were good. (day1) The chicks started showing issues after 24 hours and I had a lot of pasty butt within 24 hours. I cleaned the pasty butt. (1 chick died) (day 2) I changed the chicks to medicated feed and put probiotics in the water. I also started crushing their food into smaller pieces for easier consumption. Continued to clean pasty butt. (2 chicks died) (day 3) found some bloody stool so I suspect Cocci. I called the hatchery and they agreed so I put the brooder on sulfa in the water. Still a lot of pasty butt. (1 chick died) (day 4 - today) started out great! The chicks had been on sulfa for 24 hours. They were chirping loudly and zooming around the brooder. Everyone looked great except for I chick was a little sluggish and died around noon. At 3pm this afternoon, all chicks looked great. We were feeling good. By 5pm - 2 were dead. The others looked great. At 7 pm another died. I'm dreading going back out there because all the chicks look great and I fear more will die Maybe all the pasty butt cleanings stressed them out too much. The brooder has been in a high stress situation dealing with all the pasty butt. Over 50% of the brooder had pasty butt. The brooder was very clean and sanitized so I'm sure there were not residual issues prior to putting the chicks in the brooder. I've never had these issues so I'm sure there was nothing to transfer but we always sanitize. The latest chicks to die clearly didn't have pasty butt and appeared to never have had it. Of the 7 deaths, 3 were silkies and the others of mixed breeds. 3 of the 7 deaths had no sign of having pasty butt. I've been closely monitoring the temperatures and they are within range for bantums. The brooder is big enough that if they get hot, they can get away but most of the time they are scattered around so it looks like the temps are acceptable for them. I'm not sure what to do and any and all suggestions are greatly appreciated.