I hadn't read this thread before, but now that I do ...
Mine (26 chicks almost 3 weeks old) started having orangish poos early on too. And they are stinkier than the other poos, and rather runny.
They also have greenish poos, and blackish ones, which are more well-formed and less stinky (and smaller in volume too).
(Whoever thought we'd be so involved with the details of poo!?!?!?)
My chicks were all vaccinated for cocci, and they all LOOK fine, very alert and don't seem to be ragged (except they do look funny with all those feathers coming in) and running all over the place and many trying to fly. I think everything is normal with regards to growth and behavior. (Except one red sex-link who is still quite small compared to the others ... I think the banties may catch up to her!)
I am not sure. I give grit and feed them various treats (egg yolk, dandelion, strawberry tops, grated carrot, and they have eaten ants and a few have been outside and sampled weeds, grass, and bugs. They were only allowed outside yesterday, and the poos started the first week.
I am CERTAINLY no expert (this is my first batch of chicks) but I wonder if what you are describing might not be normal? I hope that the orange-y poo is normal. In my chicks it is brownish-orangish.
I don't know if someone more knowledgeable will offer information. Maybe the subject line is causing people to think you mean something else? I would like to know myself, but I hope that you and I both have nothing to worry about.
trish