If you google anything about protein and poultry feed, you will find an huge amount of information. You will need to weed through a lot of links to threads like this to get to the science, but there is a TON of science on this.
Of course there is. But spelling it out is perhaps beyond the scope of this forum?
One of the questions I often have is how to translate the information about poultry feed that comes from The Industry, where birds are only expected to live a few weeks (Industrial broilers) or a few months (industrial layers), to something that is useful for birds we expect to be healthy & productive for perhaps years.
A lot of threads on here try to use studies from broilers(patented 4 to 6 way hybrids that get to slaughter weight in 6 weeks) and apply them to our chickens. There is a problem with hybrid broilers--a muscle atrophies. The person that read about it was worried that their chicks would have this problem and asked if anyone had seen it.
No one had because those chickens are not like ours. They also do not metabolize feed like ours do. If ours were like them, they would be ready for slaughter in 6 weeks!
Edited by ronott1 - 1/17/16 at 7:27am