To give the birds something to do try digging up the run so they dust and search for bugs, worms etc.
Take a look at https://www.backyardchickens.com/t/645057/fermented-feeds-anyone-using-them/6130#post_15866108, most people are using plastic buckets to feed large flock such as yours.
Take a look at https://www.backyardchickens.com/t/645057/fermented-feeds-anyone-using-them/6130#post_15866108, most people are using plastic buckets to feed large flock such as yours.