I fill a feeder of layer pellets and give free choice. I feed a couple handfuls of scratch in the morning when I turn them out in the yard.
Depending on the contnets of the scratch you could feed more. I buy a kind with corn wheat, oats and barley in it. That is basically what is in the pelleted food I feed so it's 6 of one half dozen of the other.
If you were feeding a corn only scratch, I wouldn't feed them a ton of it because they may fill up on it instead of eating the complete feed that you are feeding.
The scratch that is available where i live has extremely low protein levels, so you have to consider that if you mix it with your regular feed, you're lowering the protein, calcium, whatever levels of the feed.
I've never bought scratch for my chickens. It's not necessary at all. Just a treat.
To give them a treat to scratch for and to get them used to coming up to me I do give them treats though.
I toss them either black oil sunflower seeds, or a regular wild birdseed mixture, and if I have some already I have tossed out deer corn (whole kernals) with the other stuff for treats instead of "chicken scratch"
For layer pellets or whatever their regular feed is --- just keep the feeder full constantly. For 20+ birds I would definitely have at least 2 feeders so the smaller or lower-ranking birds have a chance to get fed.
I should have explanded my self better.
I feed a 21% protein feed mixed with a 14% protein scratch that is a all grain pigeon feed.
When I mix it I mix 60% (lbs) feed to 40% (lbs) scratch. That mixture puts me at a 18.20% protein mix.
A good whole grain scratch can be some what good for chickens in moderates. Whole grain scratch can be a good sorse of fiber, vitamins, minerals and carbohydrates.
Carbohydrate rich foods are the primary source of energy for all body functions. The body breaks down carbohydrates, or carbs, into fuel for use by your cells and muscles that's why eating a moderate amount of carbohydrates is necessary.
It's also why folks say it makes your chickens "hot". Not hot like over heated, but it gives them energy. I think people misunderstand the term "hot" when in reference to feedstuffs. Corn and other carbohydrates are considered energy producing or "hot" grains.
And honestly folks, look at the ingredients in your feed and look at the ingredients in your scratch. Sure, the "complete" feed has vitamins and minerals and what not, but how many of you feed a processed feed that has "grain by-products" listed? The scratch is whole or cracked grains that you can see what they are so how is that "bad". Seems to me that's backwards logic.
Do NOT send me hate mail on this.....
I know the protien should be at certain % depending on age and growth and production levels and generally speaking scratch grains do not contain the same levels of protien, but why so many people are "anti-scratch" I have yet to figure out. No, it shouldn't be the bird's only source of nutrition if it is not at appropriate levels of protien for growth and developement and production of the bird, but neither should potatos and bread be ours. Likening it to "candy" or potato chips is, IMO, a bit misleading.
Do birds lay as well on a cracked corn based scratch as they do on a "complete" ration - no they don't(first hand experience, here). Will they die of malnutrition? Probably not( I won't say definately, cause I've not seen every bird on it. I do know folks who only feed it though and their birds are by no means on death's door).
Fact is, before companies like Purina and Dupont and TSC spent millions of dollars in research on chicken nutrition, folks were feeding vegetable scraps and scratch grains to chickens and chickens were breeding and laying and growing on it. It hasn't been until recent years that there has been such focus on animal nutrition and feeding "complete" feeds. Horses used to eat oats and hay. Cows used to eat corn and hay. Chickens ate scratch and scraps and pigs ate what ever was slopped in the trough after dinner.
As I said before, I feed my birds a locally milled complete ration and throw in some scratch on the side. But in a pinch, I'd feed them just the scratch. Just like I'd feed my horses just plain oats if I had run out of the feed I have specially milled for them. IN fact, I did have one horse who ONLY ate oats twice a day with his hay and he was perfectly healthy. But that is a different story.
Point is, you can feed scratch grains to your birds, the chicken feeding police won't come and arrest you.