Several different issues have been raised in such a short thread. I’m with ‘Canoe on the drugs. I’ll use what I think appropriate to treat something but I am not going to create a superbug by using drugs that I deem unnecessary. For me to use any drug, on me or on my chickens, is extremely unusual, though I do use Frontline and Heartguard regularly on my dogs. I’m not going to be silly about it.
What can you do to keep your flock healthy when introducing new chickens? That’s the main question. There are extremely few diseases that can be transmitted through the hatching eggs. If the hatching eggs come from an NPIP source, that’s about as safe a way as you can get them. That includes hatchery chicks.
But once the chicks come out of the shell, they can be exposed to a lot of different diseases. Again hatcheries practice really good biosecurity so I consider shipped chicks to be extremely safe. But when those chicks hit the feed store, they come into contact with people. While most feed stores keep the public from handling the chicks randomly, it is still possible that they could pick up something from someone that has chickens at home and just walks by or maybe the person taking care of the chicks has chickens at home. It’s not likely but it’s possible. Personally I wouldn’t worry about those chicks bringing something home but some people do.
Many flocks develop flock immunities to certain things. They may show absolutely no symptoms but still be a carrier. Coccidiosis is a great example but there can be others. So it’s possible new chickens could bring in a new disease to your flock or that your flock could infect the new chickens. Some people use quarantine to help with this. They house the new chickens (regardless of age) well away from the existing flock for maybe 30 days. Some diseases spread by sharing drinking water, eating each other’s poop, or just floating in air. The more you can isolate them the better your quarantine. If you raise the chicks in a brooder, you may be doing that anyway.
This should show up any diseases the new birds have been recently exposed to but does nothing for any that either flock has developed an immunity to. Even with your baby chicks they may have been exposed to a strain of Coccidiosis but develop an immunity to that in the brooder. Normally I’d suggest choosing a potentially sacrificial member of your current flock with the new birds to check for these “immunity” diseases, but with your chicks I wouldn’t do that.
I think there is something very important to realize. When your new chicks are introduced to the older chickens, they are going to become exposed to whatever either flock has. That is unavoidable unless you forever keep them separate. You cannot forever keep them in a sterile vacuum. Of course each disease is different but in general, babies can develop immunities easier than adults, especially for the common things that flocks develop immunities to. I want my chicks to start working on flock immunities as soon as they can. I feed mine some dirt from the run a couple of days after I take them out of the incubator and give them some more of that dirt every four or five days. This not only gives them grit and any probiotics the adults have, it gets them working on flock immunities while they are in the brooder where I can control how wet it is and better observe them. I just feel like I raise healthier chickens if I let them work on flock immunities and build up their immune system instead of keeping them in a sterile environment.
These things don’t come with guarantees. This is my approach and my opinion. Not everybody will agree with me.
