can failure to thrive happen at any age?

[spish]

i have a few 4 month old chickens (araucana crosses) i was pretty sure from early on that is was 3 hens, 2 roos, which was confirmed on here.
anyhow the 3 hens are doing fab, so is one roo, but the other roo always looks sick, especially after just getting over cocci too. he's always pale (comb and wattles) hangs at the back of the crowd, doesnt crow and just seems to slowly be getting worse (we thought we'd lost him the other week he was rolling round the floor couldnt walk not eating, pooping yellow runs etc etc but after treatment for cocci he got back to his usually quiet, sick looking self.
anyhow i noticed yesterday how small he is compared to his brother, and how thin his legs are! (they are even thinner than the hens legs!)
so im wondering, as he's not been good since hatching, could it be a long drawn out failure to thrive case...Or simply a way down low in the pecking order roo?

 

[justbugged]

Birds are fragile. So any of your theory's could be true. Or it came it mind, that it could be worms. So it is about throwing a lot of things at them and hoping for the best.

I hope that by bumping your question up that someone else will have a better answer.

 

[Cuban Longtails]

Let him go... he's not good to have in your flock. He's a liability to the overall health of all of your birds. As you said in your post, he's always been sickly and weak and continues to be so. Is that something you want him passing on to any potential offspring?

 

[spish]

i dont think he'd get a chance to produce offspring, he's quarter the size of any ladies and is in the bottom of the pecking order of roo's (we have 7 out there)