Too much heat, not enough heat. Shipping stress, perhaps an immature digestive system. Be sure to check your chicks frequently, and if you see any poo build up, clean it. If you allow it to build up, it can block the vent, and kill the chicks. Broody raised chicks never have PB (that I know of). Mama hen takes those babies out into the yard and gives them plenty of beneficial bacteria and fungi to build up a healthy gut flora. Her chicks eat soil, as well as snacking on chicken poo. They are running around at what ever the ambient temperature, but duck back under her to warm themselves before they get too chilled.
Brooder raised chicks benefit from having an environment that comes as close as possible to matching the broody experience: Heating pad brooding: Give them a heating pad cave to snuggle under. A nice safe warm spot. The rest of the brooder can be at what ever the ambient temps are. (I prefer to brood later in the spring so the chicks aren't facing winter weather.) Give the chicks a plug of sod from your yard, or even from the chicken run so they can load their guts with beneficial bacteria and fungi. They will also get some grit (also helpful at preventing PB, IMO.) as well as some minerals, first greens, some seeds and insects, a few worms to fight over, first dust bath, and lots of opportunity for developing their foraging skills.
We just got our first baby chicks today, there about 3-4 days old. Should we give them probiotics now, or wait a few weeks and then start the 3 days on, 2 weeks off cycle.
I can see no benefit of waiting till they are older to start those probiotics. If I bought them, I'd be using them in the first week. The sooner those chicks get their gut flora built up, the sooner they will have a healthy and strong immune system. I used probiotics with my first flock. But, since being mentored by BeeKissed, and doing a lot of my own research, I have moved towards a more natural method. My whole flock gets fermented feed, and the chicks get a plug of sod soon after hatching. The chick has natural immunity received from her mother. This is strongest within the first 2 weeks and then starts to wane. So, it's important to use this window of opportunity to load that gut with beneficial organisms. That soil will also give the chicks their first exposure to cocci and other pathogens they will encounter in your yard. (Don't panic!) Cocci are a natural flora, found in every chicken gut. It's only when the bad guys outnumber the good guys that the chicken gets sick.
