If you want to provide a balanced diets using scratch grains, you will need to provide a variety of different food types and supplements to provide the extra vitamins, minerals,  amino acids etc. to meet the birds requirements. It will also have to be mixed extremely well or each bird may get different amounts of those supplements.
		
		
	 
This! But how do you choose the variety? I can't find much on the nutritional value of various grains/seed. 
 
Sorry, not tables, recipes. 40% this, 20% that... I compiled a few of them and made a table. There were many more out there, but I stopped when I realized there was little rhyme or reason except for protein/carbs or preference against corn, soy (gmo), or alfalfa.
 
I'm just not a fan of processed foods. I don't care how fast it goes from whole grain to pellet. Do you think there'd be an aroma in the process? What would you be smelling? Why would you check the manufacture date? Could it be that the uber-processing creates a huge surface area and potential for oxidation and reduced nutritional value? I'd rather keep natures tupperware intact and keep my grains whole until I crack it open or the chicken does. I might be a hippie in that I like to mimic nature when growing/raising plants animals, but the prepper in me wants to be able to provide food if I'm ever unable to get access to those convenient pellets. I can't plant a pellet. 
 
I was even considering sprouting the grains to activate enzymes (protein), increase digestibility, and eliminate the need for grinding. I realize that certain supplements won't be adequately provided for with my grain/seed choice and I'll have to settle for powders, and I'm fine with that. 
 
Personally I only own one acre, but my neighbors are friendly so they've got access to 5+ more without the ability to rotate through it.
 
Also, I should mention that I may or may not have "modern layers", I don't really know what that means. I've got dual purpose birds, 3/5 are heritage breeds and the other 2 have family members that are.