Most farm and feed stores sell layer feed or flock raiser feed. I prefer one that is homogenizedcrumbles or pellets, where the chickens cannot pick out the “tasty bits” they prefer, leaving the rest. That is better than eating mixed seeds, and a balanced chicken feed is all they need, with all of the protein and other nutrients. Those along with granite poultry grit and crushed oyster shell are needed for a healthy flock. If you feed scratch grains and sunflower seeds as a diet, they will be deficient in protein, vitamins, and minerals. I prefer Purina or Nutrina feeds, but there are others that are good as well.