Not sure where you are going with that, because the fact remains you can leverage a better price in bulk, and even a better price on locally milled stuff sometimes...
A mill, that is a real mill sells a feed mix made from local grains.
What is a real mill? Not all areas of the US have all the available grains locally, and thus they choose different formulas to accomplish their goals, that does not mean they are not a real mill, it just means they do what they have to do based on their region, location and availability...
You cannot dissect a feed mix that is commercial made.
Sure you can, there is no shortage of people on this forum that dissect commercial feeds or seek feeds that have this or that or lack this or that ingredient... And just because it's a commercial feed does not make it superior to a properly mixed custom feed... A custom mix done properly can be just as good, there is no magic to commercial feeds, just a planned out nutritional profile...
There are chemicals in the feed that in some % enhance the lower protein grains.
Generally the inferior protein is simply balanced with amino acids be them natural or synthetic not chemicals...
This allows the company to cheat on real protein.
No it allows the company to optimize the protein in the feed based on the necessary amino acid balance required for the animal and reduce waste, it's not cheating it's tailoring the feed to the requirements of the specific animal while reducing waste... That is not cheating that is optimizing and reducing waste... Back in the day it was not uncommon for feed companies to produce 30% or higher protein plant feeds for chickens while trying to get the proper amounts of Methionine and Lysine, today they can do a 16% crude protein and then toss in some Methionine and Lysine additive and/or meat by-products and get the same results with less waste at a lower cost...
So to use soymeal and grains and a premix would dilute the chemical and cause the commercial feed not to be what it advertised.
Dilute what chemical? If a decent mix of soy meal and grains is used the nutritional profile can be maintained as well as the amino acid requirements, especially if a supplement like Diamond V as I suggested is added to fill in any possible nutritional gaps... Again there is no magic in commercial feeds you can mix your own of equal quality if you plan it out, and in many cases leverage an overall savings in bulk if you have a local mill... Heck there are local mills all over the US now making regional 'commercial' feed blends even further blurring the difference between a custom mill mix and commercial mix...
If you feed 50lbs+ a day, you are producing enough meat or eggs to pay for it.
You are incorrect and wrong in your assumptions...
I don't raise meat and I sell a very limited number of eggs... Some of my birds like my peafowl are mostly 'pets' and offer little return at this time especially since most are not mature and thus not laying, and even when they do start laying, they hens generally won't lay enough eggs to pay for the entire peafowl's yearly feed bill... Same with my flock of guinea fowl, I can't even give their eggs away around here so they produce zero income, the same applies for my bantams, no one is interested in buying bantam eggs around here either... In time I certainly might turn a positive return in my newly started breeding programs and that is the goal, but I'm certainly not at that point right now... I 100% guarantee you that my feed cost far exceeds any monetary return from flock at this time,. that is not speculation that is fact... And even if they were fully paying for themselves I would still pursue savings on feed within limits, there is simply no reason to waste money just because I'm making money...
There is no local mill by me so that route is not an option, but saving a few dollars a bag by driving 20-30 miles extra is an option, so I do that over buying locally when I have the time to make the drive and leverage a big enough purchase to defer the gas cost...
When my last batch of Cornish were ready for butcher I was feeding 3000lbs. a day. Feed bins not bags. I'm also not a backyard chicken man, I'm a farmer that likes chickens.
I raise 300 meat chickens a yr.
And thus your goal is to turn a profit as a business venture and run it as a business, the same can not be said for many others on this forum...
And if you were raising 300 meat chickens and feeding 3000lbs of feed a day you really should figure out where all those tons of feed waste was going... At 8/9 weeks a single broiler should only be consuming about 3 lbs of feed a week for a total of about 900lbs of feed a week for your flock of 300, that comes out to be about 128lbs a day a far cry from 3000lbs... You could have fed a flock of 7000 birds with that 3000lbs a day....