That's exactly basically what I was trying to say. It's was stated that the food would go further. It's just not the case. I should have clarified that by measurable I meant statistically significant.
There are several variables the studies don't account for. But that's not really the aim is...
So if I pump an orange with probiotic water so you can now only eat 3/4 of an orange instead of a whole orange. Am I getting more nutrition or less?
If you want to get into the more scientific exploration of how fermenting may deactivate some anti nutrients and make it more nutritious that way...
If a domestic breed of chicken.... no it won't be enough for ethical well-being and optimum health.
Providing them commercial feed won't stop them scratching and hunting for goodies and consuming all the scraps you can provide. There is no downside to offering a complete feed on top of scraps...