Hi Leah, it sounds as if you have two batches of chickens. Are these your first chickens, or have you kept poultry on your premises before?
Could you tell us more about the three older chickens? You say these are 8 weeks older than the others. What age were they when you first got them? Did you get them as young chicks, and then add some more younger ones a few weeks later, or did you go back and get some older birds after you got the younger chicks?
And how old were the younger chicks when you first got them?
I’m just wondering if all your birds arrived at the same time, in two age groups of older and younger chicks, or whether you have two batches because you went back later, and added some more. Also, have any of the older ones died, and if so, how old were they then?
It would also be helpful if you could post us the link to the breeder’s chicken farm. A possible problem with buying rare purebred birds is that they might come from a very small gene pool, and thus be inbred to some extent. Another is that the breeding birds might perhaps be shut up together as a small group of a cockerel and 2-4 hens and thus be in very close contact for some weeks without the benefits of sufficient space for normal free ranging. Much would then depend on standards of cleanliness and indeed, the health of the parents, to produce strong and healthy chicks.
When you visited the farm and got the chicks, were you able to form an opinion about the conditions the birds were kept in? I expect the chicks were all in together and the parent birds were somewhere else, but did the premises seem clean, with clean water drinkers etc? Were the chicks still young enough to need extra heat? At that stage, they would all be vulnerable to any kind of environmental infection, and in the case of Mareks this might arise from virus particles from the feather dust of previously infected birds lingering in the environment. It is fir this reason that, once present, Mareks is so difficult to eradicate, and therefore quite common in unvaccinated purebred flocks.
As Mrs Biscuit says, the most dangerous time for coccidiosis is usually at the chick stage, when the chicks are pecking around in a heated brooder in damp, contaminated bedding and picking up oocytes from each other’s infected poo. However, from what I have read, this is unlikely to appear in older birds, off heat and out of doors in normally clean conditions. If a lot of them were so badly affected that they actually died, I expect the blood in poo would be very noticeable.
See https://poultrykeeper.com/digestive-system-problems/coccidiosis-in-chickens/
I agree with Mrs B. that you need to talk to your vet about this. Something uncommon appears to be going on here, and whilst we can give advice from our own experience about common management or health problems, we can’t do more than hazard a guess about anything more serious, without seeing the birds or even photos. I hope we might have been able to fill in a bit more of the background and given you some leads to raise with the vet when you speak to them, and I hope very much that all will be well if you can get a professional opinion on whatever is hitting your flock so hard.
How are they this morning?
