Black/green poop throughout flock

[Isabelstu]

This morning I was cleaning out my coop when I realised that most of my entire flock had black poop… what was even weirder to me is that when I looked at the wood chips underneath the poop it had stained a vibrant dark green, the day before I did feed some left over red cabbage and so far I have treated with apple cider vinegar in the water. Should this be a cause of concern?

 

[Perris]

Photos of the poops would help the rest of us to help you.

 

[Isabelstu]

Photos of the poops would help the rest of us to help you.

 

[MotherofOrpies]

Usually black poop comes from protein ( whenever I dig up rainworms and they eat a lot, the poop turns black) and the deep green can come from the red cabbage, alternative cause could be blood, but if they look happy, just wait a day

 

[rosemarythyme]

Betting it's the red cabbage, as it stains enough to be used as a natural dye.

 

[Perris]

as the others have indicated, it's probably nothing to worry about.
Keep an eye on them, and please let us know if things take a sudden turn for the worse.

 

[Wyorp Rock]

Poop can have a wide range of colors and textures. Diet often dictates color.
Wood Ash will turn poop black, so will eating dark soil.

Sounds like the OP gave Red Cabbage, so that would cause the color of poop they are seeing.

Photo reference and article link
https://the-chicken-chick.com/whats-scoop-on-chicken-poop-digestive/