"Scratch" is a very generic name for a grain that can be tossed on the grown to make a bird "scratch" at the ground. it can be as simple as crack corn or a 15 grain mix.
For the most part the "scratch:" you will get at the feed mill
(cracked corn, wheat, oats, & millet) will be a low protein (9%) high carbohydrate grain mix that is OK to feed as a treat.
I feed about 1 cup of "scratch" per 5 large fowl birds.
I feed a 16% protein scratch grain that I mix. Basically it is a 14% all grain pigeon feed with some extras I add in
The 14% pigeon feed contains grains like ( AUSTRIAN PEAS, CANADIAN PEAS, MAPLE PEAS, MUNG BEANS, VETCH PEAS, POP CORN, LINSEED (Flax), MILLET, GROATS, BROWN RICE, SAFFLOWER, BLACK OILED SUNFLOWER SEED, BUCKWHEAT, WHEAT)
To the 14% pigeon feed I add BLACK RAPE SEED, HEMP SEED (Whole), GROUND UNSALTED PEANUTS
Chris