7 week old chicks dead no symptoms

[TinyBirds]

I would separate the chicks and give them the antibiotics separately, to avoid giving antibiotics to egg layers. I am in the same boat as you, losing some chicks but the adults are all fine. I think having the chicks out with the adults probably causes the problem. My chicks got bugs on them from the adults and I used a drop of neem on each chick, and separated them from the adults, and they're doing much better now. Nice to see them active again and not sickly looking. I think the neem also acts on the cocci so if you try that, it might avoid having to use antibiotics if you don't want to resort to that yet. I got the neem from Mountain Rose Herbs (something like that) on-line and the bugs were gone within a few days. Neem is dangerous orally though so only use it externally. People use it for head-lice too (neem shampoo). Mites can suck blood out of the chicks and cause them to die.

I forgot to mention, if the ones dying are light-weight and not growing well, it could also be worms. We have roundworms here and even the adults suffer from it. When it gets bad I put garlic and cayenne pepper in their food for a few days to get the birds back on track. There are herbal wormers to buy also, but the ingredients are just garlic and cayenne, so you can just put those in the food instead of buying the wormer. I don't use chemical wormers (not even for our sheep), since the worms just become resistant anyway. The herbal remedies seem just as good and probably safer. I don't use the neem on laying-hens though, to be on the safe side (since we eat the eggs) - just the garlic and cayenne pepper.