For sure I do need to work on the 'leave it' cue, because off-lead she'll ignore it in many places. She's only been with us for about 3-4 weeks, and was partially trained by a few different people before so I'm going back over to refine those basics. But I hoped there was some protocol for teaching to avoid specific 'foods' without me having to say 'leave it' every time though - I mean, the chickens free range in our/her own backyard.
Unless she is trying to correct a deficiency in her diet?
I don't think so: because she did it from the very first day we got her home, and must have a different diet here than before but the poop eating continues. I think it's just an established behaviour? But, I'm now adding organ meats and real foods like that to her diet, maybe it will help.
Is there specific deficiencies commonly indicated by this? - I think her behaviour is broadly within the 'normal' range of poop interest for dogs. It's not like she's obsessively eating all the chicken manure, she just goes for 'special smelling' bits, but she's persistent about it when she's found one.