Because nutrition is really important when they are growing, chicks should be supplied starter or start and grow feed. The only "treat" we gave our growing chicks was chopped hard cooked egg yolk. Once you start feeding something other than commercial feed, you will need to provide grit too.
At about 18-20 weeks, you can feed layer feed, which provides additional calcium for egg laying. You also need to provide oyster shell.
Your flock will love the seeds and veggies you mentioned. Too much corn is not good, as it makes them fat which can cause problems. I think you're going to find that all they'll eat of the hay (we have timothy and alfalfa) is the leaves. They might try to eat the stems, but that can cause crop impaction, so I chop the hay into small pieces.
Our flock is fed a vegetarian diet; vegetarian layer feed or certified organic layer feed being their main source of required nutrients. They have free-choice access to grit and oyster shell.
They also forage our fenced 2 acres from sunup to sundown. Although we've decided not to feed animal meats to our flock, they do eat worms, bugs, grubs, grasshoppers, crickets when foraging.
This past winter, we have been feeding our flock lots of greens since they don't have access to the yard. (We had over 4' of snow.) We have a two-tier wire-basket hanging planter that is made of heavy gauge steel. We hang it from a beam in the barn on a bungie cord. We fill the lower basket with veggies, chopped hay or fruit (a quartered head of cabbage, chopped hay, cored & quartered apples, etc). The birds have to jump to get the treats in the basket. The top basket is loaded with rocks to keep the basket kind of low for the chickens while it gets emptied.
We also feed organic fruits and veggies, most grown on our farm. Our flock loves greens (veggie tops), kale, Swiss chard, lettuces, red and green cabbage (they especially love the red), Brussels sprouts, green beans, carrots, corn, tomatoes and all types of summer and winter squash.
They go crazy for fruit like cranberries, blueberries, plums, apples, grapes and peaches. Sometimes I puree the fruit to mix with their feed.
We also give them chopped hard cooked eggs, buttermilk, plain yogurt w/active cultures, low-sodium cottage cheese with their feed and provide organic grains (rolled oats, barley, wheat) and fancy scratch, sunflower and flax seeds.
We give them buttermilk, yogurt or cottage cheese several times a week, sometimes mixed with their feed or with another treat - they love it with fresh berries or chopped tomatoes.
I add 2-4 cloves of crushed garlic per bird to their feed, but they also love to eat it off a spoon. They drink the buttermilk out of a small feeder dish.
This past summer we had a great deal of 'surplus' sweet corn which I processed for winter treating. I dried some corn kernels in my oven and blanched some whole ears for freezing. I cook the frozen corn on the cob, cutting each ear into thirds and give each bird one piece. It keeps them busy, provides them semi-warm corn on a cold winter's night and it's amusing to watch them attack their little cobs. I just have to watch that the greedier birds don't finish their piece and try to grab someone else's!
When I make corn or pumpkin muffins for us, I make some without the added sugar and salt, and substituting whole egg for the oil asked for in the recipe. This is the only bread we feed our flock.
Our flock got lots of fresh veggies and blueberries from our garden this past summer and they nibbled on parsley, rosemary, basil, thyme, oregano, sage and garlic from my container gardens too.
Too much salt is not good for your flock at any age; it can cause salt poisoning. Too much calcium is not good for chickens that aren't laying eggs yet. It can damage the kidney and liver.
There are many good books available on raising chickens. Check your local library first. Watch out! Chickens are addictive!
regards,
keljonma
