Blah! sory it took me so long- Im talking into my computer and parrots are screaming in the background, but here it goes-
Newer work using sequencing and metabolomics (e.g., Kers et al., 2018; Józefiakk et al., 2020; more recent Frontiers and Poultry Science reviews through 2023–2025) has only reinforrced that they host the most diverse microbial populations and produce SCFAs like butyrate, which support gut health.
But the key clarification — and this is where more recent literature sharpens the older papers — is that:
They are the main fermentation site… not the main nutrition site.
That’s why newer reviews (Jha & Berrocoso 2015; Kierończyk et al. 2022; recent Poultry Science reviews) frame the caeca as:
- a secondary fermentation system
- a microbiome modulation hub
- more influential when diets are low quality, high fiber, or poorly digestible
Which actually lines up perfectly with the older studies you quoted — especially the ones showing benefits under
protein-deficient or poorly digestible diets.
So the takeaway hasn’t changed — it’s just clearer now:
The worse the diet, the more the caeca matter.
And that’s really the point in the fermented feed discussion. If you’re feeding a
balanced commercial ration, the bird is already designed to extract what it needs
before the caeca ever get involved (in theory for formulated diets). Fermenting doesn’t “unlock” some hidden system — it just shifts microbial activity earlier, often less predictably.
If you’re feeding
whole grains, fiber-heavy inputs, or marginal diets, then yes — the caeca become more relevant. But that’s not because fermentation is required… it’s because the bird is compensating- of course this is just the opinion of a few in the newer studies.
But they’re also not saying the caeca run the show — they’re saying:
the caeca matter most when the bird is dealing with things it couldn’t digest earlier.
Edit: I have a pHd, but a professional at typos. Whoops.
